Manual on LaserEmitters andFlight Safety Approved by the Secretary General
and published under his authority

First Edition — 2003
International Civil Aviation Organization
Manual on LaserEmitters andFlight Safety Approved by the Secretary General
and published under his authority

First Edition — 2003
International Civil Aviation Organization
The issue of amendments is announced regularly in the ICAO Journal and in themonthly Supplement to the Catalogue of ICAO Publications and Audio-visualTraining Aids, which holders of this publication should consult. The space belowis provided to keep a record of such amendments.
Adequate lighting is necessary for all visual tasks. An ICAO formed a study group in 1999 to evaluate the laser excess of light, however, can detrimentally affect vision to risk and consider whether new Standards or Recommended the extent of rendering it ineffective. In aviation, a pilot Practices (SARPs) were necessary.
may experience high levels of lighting when flying into thesun or looking at very bright artificial light sources such as The study group consisted of experts in ophthalmology and searchlights. The invention (in 1957) of the laser* is a vision care, light engineering and physics, flight operations significant addition to the known aviation-related problems and regulatory aviation medicine. These experts were associated with high-intensity lights.
nominated in part by four Contracting States: Canada,Netherlands, United Kingdom and United States and in part Laser is an acronym for light amplification by stimulated by the Aerospace Medical Association and the International emission of radiation; this technique can produce a beam of Federation of Airline Pilots' Associations.
light of such intensity that permanent damage to humantissue, in particular the retina of the eye, can be caused At the first meeting of the study group, documentation was instantaneously, even at distances of over 10 km. At lower presented indicating that there was considerable intensities, laser beams can seriously affect visual international concern that lasers might pose a significant performance without causing physical damage to the eyes.
and increasing risk to flight safety and that without ICAO There are, however, many useful applications of laser action, development of necessary controls in individual technology, such as high-speed automatic scanning of bar Contracting States would be inconsistent, insufficient or codes, laser printing, welding and cutting, micro-surgery, communication by means of fibre optics, recording ofmusic, gyroscopes, light displays and the ubiquitous laser During 1999 and 2000, the Aviation Medicine Section of pointer used by lecturers worldwide. Lasers are associated the ICAO Secretariat, with the assistance of the study with almost every aspect of modern life.
group, developed the laser-related SARPs that are nowincluded in Annexes 11 and 14 to the Convention.
Whilst protection of the pilot against deliberate or However, these SARPs do not provide the necessary accidental laser beam strikes has been of interest to military practical guidance for implementation of relevant aviation medicine specialists for many years, it was only regulations in States. The study group, therefore, with the advent of the laser light display for entertainment recommended that a manual be written focussing on the or commercial purposes and subsequent accidental medical, physiological and psychological effects on flight illumination of civil aircraft from such displays that civil crew of exposure to laser emissions.
aviation medicine specialists have become more concerned.
The information and guidance material provided in this By 2001, many pilots had experienced incapacitation manual is primarily directed to decision-makers at following accidental laser beam strikes. Over 600 incidents government level, laser operators, air traffic control have been recorded worldwide, the majority of reports officers, aircrew, aviation medicine consultants to and coming from the United States (see Chapter 4, page 4-1 for medical officers of the regulatory authorities, and doctors a summary of two significant incidents). It may be expected involved in clinical aviation medicine, occupational health that most civil aircraft laser beam strikes will be and preventive medicine. The manual is aimed both at inadvertent, but powerful laser emitters that can be reducing the need for regulatory authorities to seek accurately targeted are now available at relatively low cost, individual expert advice and at reducing inconsistencies so the possibility of malicious use of such devices in the between Contracting States in the implementation of future cannot be ignored.
In view of the increasing risk to flight safety posed by themore widespread use of laser emitters around airports, ∗ The term laser has more than one meaning, see Glossary.
Manual on laser emitters and flight safety In addition, it can be used to support training provided by parties outside ICAO would be appreciated. They should be operators to flight crew with respect to the effect of laser emitters on operational safety. It is recommended that theinformation contained in Chapter 4, particularly in relation The Secretary General to preventative procedures, be included in the operations International Civil Aviation Organization 999 University Street This manual contains information and guidance provided Montréal, Quebec H3C 5H7 by the study group. Comments from States and other TABLE OF CONTENTS
Chapter 4. Operational factors and
training of aircrew . . . . . . . . . . . . .

List of abbreviations, symbols and units . . . . .
Chapter 1. Physics of lasers . . . . . . . .
4.2 Situational awareness . . . . . . . . .
4.3 Orientation in flight . . . . . . . . .
1.1 Introduction to laser emitters . . . . . .
4.4 Preventative procedures . . . . . . . .
1.2 Components of a laser . . . . . . . .
Chapter 5. Airspace safety . . . . . . . . .
1.4 Beam properties . . . . . . . . . . .
1.5 Characteristics of materials . . . . . .
5.2 Airspace restrictions . . . . . . . . .
5.3 Aeronautical assessment . . . . . . .
Chapter 2. Laser hazard evaluation . . . . .
5.4 Control measures . . . . . . . . . .
5.5 Determinations . . . . . . . . . . .
5.6 Incident-reporting requirements . . . . .
2.3 Accessible emission limit (AEL) . . . .
Chapter 6. Documentation of incidents after
2.4 Laser hazard classification . . . . . . .
suspected laser beam illumination . . . . . .
2.5 Nominal ocular hazard distance (NOHD) .
2.6 Optical density (OD) . . . . . . . . .
6.3 Documentation . . . . . . . . . . .
Chapter 3. Laser beam bioeffects and
Chapter 7. Medical examination following
their hazards to flight operations . . . . . . .
suspected laser beam illumination . . . . . .
3.3 Biological tissue damage mechanisms . .
Appendix A. Notice of proposal to conduct
outdoor laser operation(s) . . . . . . . . . .
3.6 Ocular laser beam damage terminology .
3.7 Laser beam bioeffects . . . . . . . .
Appendix B. Suspected laser beam incident
3.8 Laser beam bioeffects and air operations . 3-10 report and suspected laser beam exposure
questionnaire . . . . . . . . . . . . . . .
3.10 Medical evaluation of laser beam Appendix C. Amsler grid testing procedure . .
Note.— The definitions of the terms listed below are Beam waist. The minimum dimension of a cross section of
based on a pragmatic approach. The terms defined are therefore limited to those actually used in this manual. Thislisting is not intended to constitute a dictionary of terms Buffer angle. An angle added to the beam divergence or
used in the laser field as a whole. intended laser projection field in order to ensure aprotection zone.
Absorption. Transformation of radiant energy to a different
form of energy (usually heat) by interaction with matter.
Buffer zone. A volume of air surrounding the laser beam,
all potential locations of the laser beam and all Accessible emission limit (AEL). The maximum accessible
hazardous diffuse or specular reflections, where the emission power or energy permitted within a particular maximum permissible exposure (MPE) or visual laser class.
interference levels are exceeded. It includes the beamdivergence or scanning extent of the laser beam plus the Accessible radiation. Optical radiation to which the human
buffer angle and the full range of the laser beam to the eye or skin may be exposed in normal usage.
point where the MPE or any applicable visual in-terference level is not exceeded. Natural terrain or beam Actinic radiation. Electromagnetic radiation in the visible
masks may truncate part of this volume.
and ultraviolet part of the spectrum capable ofproducing photochemical changes.
Cavity. The optical assembly of a laser usually containing
Aerodrome reference point (ARP). The designated
two or more highly reflecting mirrors which reflect geographical location of an aerodrome.
radiation back into the active medium of the laser.
After-image. An image that remains in the visual field after
Collateral radiation. Any electromagnetic radiation
an exposure to a bright light.
emitted by a laser, except the laser beam itself, which isnecessary for the operation of the laser emitter or is a Attenuation. The decrease in the laser beam power or
consequence of its operation.
energy as it passes through an absorbing or scatteringmedium.
Collimated beam. A beam of radiation with very low
divergence or convergence and therefore effectively Average power. The total energy imparted during exposure
considered parallel. divided by the exposure duration.
Continuous wave (CW). The output of a laser which is
Aversion response. Closure of the eyelid or movement of
operated in a continuous rather than a pulsed mode. In the head to avoid an exposure to a noxious stimulant or laser safety standards, a laser operating with a bright light. In laser safety standards, the aversion continuous output for a period greater than 0.25 s is response (including blink reflex time) is assumed to regarded as a CW laser.
occur within 250 milliseconds (0.25 s).
Beam. A collection of rays that may be parallel, divergent
Critical level. The minimum effective irradiance from a
or convergent.
visible laser beam which can interfere with critical taskperformance due to transient visual effects.
Beam diameter. For the purpose of this manual, the beam
diameter is the radial distance across the centre of a Diffraction. Deviation of part of a beam, determined by the
laser beam where the irradiance is 1/e times the centre- wave nature of radiation and occurring when the beam irradiance (or radiant exposure for a pulsed laser).
radiation passes the edge of an opaque obstacle.
Manual on laser emitters and flight safety Diffuse reflection. The component of a reflection from a
is unassociated with biological damage and lasts only as surface which is incapable of producing a virtual image long as the bright light is actually present within the such as is commonly found with flat finish paints or individual's field of vision.
rough surfaces. A matt surface will reflect the laserbeam in many directions. Viewing a diffuse reflection Hazard. Something with the potential to cause harm to
from a matt surface may produce either a small or a people, property or the environment.
large retinal image, depending on the viewer distanceand the size of the illuminated surface.
Hazard zone. The space within which the level of radiation
during operation of a laser emitter exceeds the Divergence (ϕ). For the purpose of this manual, the
applicable exposure limit. See also nominal hazard
divergence is the increase in the diameter of the laser beam with distance from the exit aperture, based on thefull angle at the point where the irradiance (or radiant Infrared radiation. For the purpose of this manual,
exposure for pulsed lasers) is 1/e times the maximum electromagnetic radiation with wavelengths that lie within the range 700 nm to 1 mm.
Electromagnetic radiation. The flow of energy consisting
Instrument flight rules (IFR). A set of rules governing the
of orthogonally vibrating electric and magnetic fields.
conduct of flight under instrument meteorological Electromagnetic radiation includes optical radiation, X-rays and radio waves.
Interlock. See safety interlock.
Electromagnetic spectrum. The range of frequencies or
Invisible laser beam. A laser emission with a wavelength
wavelengths over which electromagnetic radiations are either shorter than 400 nm or longer than 700 nm. Laser propagated. The spectrum ranges from short wave- sources near these defining limits may be capable of lengths, such as gamma rays and X-rays, through producing a visual stimulus.
visible radiation to longer wavelength radiations ofmicrowaves, and television and radio waves.
Irradiance (E). The power per unit area, expressed in watts
per square centimetre (W/cm2) or watts per square Energy. The capacity for doing work. Energy content is
metre (W/m2).
commonly used to characterize the output from pulsedlasers and is generally expressed in joules (J).
Laser. 1) An acronym for light amplification by stimulated
emission of radiation. 2) A device that produces an Excited state. The state of an atom or molecule when it is
intense, coherent, directional beam of optical radiation in an energy level with more energy than in its normal by stimulating emission of photons by electronic or or "ground" state.
molecular transitions to lower energy levels.
Exposure duration. The duration of a pulse or a series or
Laser-beam critical flight zone (LCFZ). See protected
a train of pulses, or of continuous emission of laser flight zones a).
radiation incident upon the human body.
Laser-beam free flight zone (LFFZ). See protected flight
Flash-blindness. The inability to see (either temporarily or
permanently) caused by bright light entering the eyeand persisting after the illumination has ceased.
Laser-beam free level. The maximum level of visible optical
radiation which is not expected to cause any visual Free radical. An atom or group of atoms in a transient
interference to an individual performing critical tasks. chemical state containing at least one unpaired electron.
Free radicals may be produced within or introduced into Laser-beam sensitive flight zone (LSFZ). See protected
biological tissue where they may cause damage.
flight zones c).
Gaussian beam profile. The bell-shaped profile of a laser
Laser emitter. Same as laser 2).
beam when the laser is operating in the simplest mode.
Laser safety officer (LSO). An individual who is knowl-
Glare. A temporary disruption in vision caused by the
edgeable in the evaluation and control of laser hazards presence of a bright light (such as an oncoming car's and has responsibility for oversight of the control of headlights) within an individual's field of vision. Glare those hazards.
Laser source. See source.
Photon. In quantum mechanics, the smallest particle of
optical radiation.
Light (visible radiation). A form of electromagnetic
radiation capable of producing a visual stimulus to the Pointing accuracy. The maximum angle of expected error
human eye. Its wavelength range is approximately from in beam direction during all projected uses of the laser 400 nm to 700 nm (between ultraviolet and infrared).
Laser sources of an equivalent power slightly outsidethis range may be capable of producing less intense Population inversion. The condition needed for light
visual stimuli.
amplification to occur whereby the number of atoms inan excited state is greater than the number of atoms in Limiting aperture (Df). The diameter of a circle over which
a lower energy state. irradiance or radiant exposure is averaged forcomparison to the maximum permissible exposure(MPE).
Power. The rate at which energy is emitted, transferred or
received. Unit: watts (joules per second).
Local laser working group (LLWG). A group, convened to
assist in evaluating the potential effect of laser Proponent. The legal entity (corporation, company,
emissions on aircraft operators in the vicinity of the individual) applying to conduct an outdoor laser proposed laser activity. Participants may include, but operation at a specific time and location.
are not limited to, representatives from the aerodrometower, area control centre, aerodrome management, Protected flight zones. Airspace specifically designated to
airspace users, local officials, military representatives, mitigate the hazardous effects of laser radiation.
qualified subject experts, laser manufacturers and thelaser proponent.
a) Laser-beam critical flight zone (LCFZ). Airspace
in the proximity of an aerodrome but beyond the Maximum permissible exposure (MPE). The inter-
laser-beam free flight zone (LFFZ) where the nationally accepted maximum level of laser radiation to irradiance is restricted to a level unlikely to cause which human beings may be exposed without risk of glare effects.
biological damage to the eye or skin.
Mitigation. Use of control measures aimed at neutralizing
b) Laser-beam free flight zone (LFFZ). Airspace in
the effect of laser beams on flight safety.
the immediate proximity to the aerodrome wherethe irradiance is restricted to a level unlikely to Nominal hazard zone (NHZ). The space within which the
cause any visual disruption.
level of the direct, reflected or scattered radiationduring operation of a laser emitter exceeds the c) Laser-beam sensitive flight zone (LSFZ). Airspace
applicable maximum permissible exposure (MPE).
outside, and not necessarily contiguous with, the Exposure levels beyond the boundary of the NHZ are LFFZ and LCFZ where the irradiance is restricted below the applicable MPE level.
to a level unlikely to cause flash-blindness or after-image effects.
Nominal ocular hazard distance (NOHD). The distance
along the axis of the laser beam beyond which the d) Normal flight zone (NFZ). Airspace not defined as
appropriate maximum permissible exposure (MPE) is LFFZ, LCFZ or LSFZ but which must be protected not exceeded (i.e. an indication of the "safe viewing" from laser radiation capable of causing biological distance). An equivalent term for skin exposure is "skin damage to the eye.
hazard distance".
Normal flight zone (NFZ). See protected flight zones d).
Pulsed laser. A laser that delivers its energy in individual
pulses lasting less than 0.25 s. See repetitively-pulsed
Optical density (OD). A physical property of a material that
quantifies the attenuation of the laser beam.
Pulse duration. The duration of a laser pulse, usually
Optical radiation. Part of the electromagnetic spectrum
measured as the time interval between the half-power comprising infrared, visible and ultraviolet radiations.
points on the leading and trailing edges of the pulse.
Manual on laser emitters and flight safety Pulse repetition frequency (PRF). The number of pulses
Sensitive level. The minimum effective irradiance from a
that a laser produces over an applicable time frame visible laser beam, which can cause temporary vision divided by that time frame. For uniform pulse trains impairment and therefore interfere with performance of lasting over 1 s, the PRF is the number of pulses vision-dependent tasks. Illumination at this level may emitted by the laser in 1 s. Unit: hertz (Hz).
cause after-images or flash-blindness.
Radian. A unit of angular measure equal to the subtended
Source. A laser emitter or a laser-illuminated reflecting
angle at the centre of a circle by an arc whose length is equal to the radius of the circle. 1 radian = 57.3degrees; 2π radians = 360 degrees.
Specular reflection. A mirror-like reflection that usually
maintains the directional characteristics of a laser beam.
Radiant energy (Q). Energy emitted, transferred or
received as radiation. Unit: joule (J).
Terminated beam. An output from a laser which is directed
Radiant exposure (H). The laser beam energy per unit area,
into airspace but is confined by a suitable object that expressed in joules per square centimetre (J/cm2) or blocks the beam or prohibits the continuation of the joules per square metre (J/m2).
beam at levels capable of producing psychologicaleffects or visual disruption.
Radiant power (Φ). Power emitted, transferred or received
as radiation. Unit: watt (W).
Transmission. Passage of radiation through a medium. If
not all the radiation is absorbed, that which passes Reflection. Deviation of radiation following incidence on a
through is said to be transmitted.
surface. A reflection can be either diffuse or specular.
See diffuse reflection and specular reflection.
Ultraviolet radiation. Electromagnetic radiation with
wavelengths shorter than those of visible radiation, for Refraction. The redirection of light as it passes from one
the purpose of this manual: 180 to 400 nm.
medium to another.
Vestibular apparatus. The organ of equilibrium in the inner
Repetitively-pulsed laser. A laser producing multiple pulses
ear. Because of its complicated anatomy, it is also of radiant energy occurring in sequence with a pulse called the labyrinth. It consists of the semicircular repetition frequency (PRF) greater than 1 Hz.
canals and the otolith organs.
Retinal hazard region. Wavelengths between 400 nm and
Visible radiation. See light.
Safety interlock. 1) A device which is activated upon entry
Visual flight rules (VFR). A set of rules governing the
to a laser laboratory or enclosure, which terminates conduct of flight under visual meteorological laser operation or reduces personnel exposure to below the maximum permissible exposure (MPE). 2) A devicethat is activated upon removal of the protective housing Visual interference level. A visible laser beam, with an
of a laser in such a way as to prevent exposure above irradiance less than the maximum permissible exposure the maximum permissible exposure (MPE).
(MPE), that can produce a visual response whichinterferes with the safe performance of sensitive or Scanning laser beam. Laser radiation that moves, i.e. has
critical tasks by aircrew or other personnel. This limit a time-varying direction, source or pattern of varies in accordance with the particular zone where the propagation with respect to a stationary frame of laser is operating. A generic term for critical level, sensitive level or laser-free level.
Scintillation. Rapid changes in irradiance levels in a cross-
Wavelength (λ). The distance between two successive
section of a laser beam, caused by variations of the points on a periodic wave that have the same phase. It index of refraction in a medium as a consequence of is commonly used to provide a numeric description of temperature and pressure fluctuations.
the colour of visible laser radiation.
attitude direction indicator maximum irradiance level accessible emission limit minimal ophthalmoscopically visible lesion above ground level maximum permissible exposure American National Standards Institute aerodrome reference point air traffic control aid to air navigation automatic terminal information service International Commission on Illumination normal flight zone (Commission Internationale de l'Éclairage) nominal hazard zone critical zone exposure distance limiting aperture distance measuring equipment nominal ocular hazard distance Federal Aviation Administration U.S. Food and Drug Administration nominal sensitivity hazard distance forward looking infrared night vision device flight safe exposure limits night vision goggles horizontal situation indicator pre-corrected power instrument flight rules pulse repetition frequency instrument landing system instrument meteorological conditions Society of Automotive Engineers spatial disorientation standard instrument approach procedure standard terminal arrival route light amplification by stimulated emission sensitive zone exposure distance temporary visual impairment laser-beam critical flight zone temporary vision loss light emitting diode coordinated universal time laser eye protection laser free exposure distance visual correction factor laser-beam free flight zone visually corrected power light detection and ranging visual effect distance local laser working group visual flight rules loss of situational awareness visual meteorological conditions laser-beam sensitive flight zone laser safety officer multifunction display Manual on laser emitters and flight safety Definitions of units
e. A term for the irrational number that corresponds to the base of natural logarithms: 2.71828183… .
Hertz (Hz). The unit that expresses the frequency of a periodic oscillation in cycles per second.
Joule (J). A unit of energy. Joules = watts × seconds.
Milliradian (mrad). A unit of angular measure used for beam divergence. A milliradian is about 0.057 degree (one
seventeenth of a degree) or 3.44 minutes of arc.
Watt (W). A unit of power. 1 watt = 1 joule per second.
Chapter 1
1.1.3 The velocity of light in a vacuum, c, is 3 × 108 metres per second (m/s). The wavelength, λ, of light is 1.1.1 A basic insight into how a laser works helps in related to the frequency as follows: understanding the hazards incurred when a laser emitter isused. As shown in Figure 1-1, electromagnetic radiation isemitted whenever a charged particle (e.g. an electron) gives up energy. This happens every time an electron drops froma higher energy state, Q1, to a lower energy state, Q0, in an 1.1.4 The difference in energy levels across which an atom or ion as occurs in a fluorescent light. This can also excited electron drops determines the wavelength of the happen from changes in the vibrational or rotational state of emitted light. As the energy increases, the wavelength 1.1.2 The colour of light is determined by its frequency or wavelength. The shorter wavelengths are theultraviolet (UV) and the longer wavelengths are the 1.2 COMPONENTS OF A LASER
infrared (IR). The smallest particle of light energy isdescribed in quantum mechanics as a photon. The energy in 1.2.1 As shown in Figure 1-2, the three basic joules, E, of a photon is determined by its frequency, v in components of a laser are: hertz (Hz), and Planck's constant, h (6.63 × 10–34 J s), as Lasing medium (crystal, gas, semiconductor, dye, E = h × v Q Higher energy state photon energy hv = Q – Q Q Lower energy state Figure 1-1. Emission of radiation from an atom by transition of
an electron from a higher energy state to a lower energy state
Manual on laser emitters and flight safety Pump source (adds energy to the lasing medium, is a partial reflector, part of the amplified energy is emitted e.g. xenon flash lamp, electrical current to cause as a laser beam.
electron collisions, radiation from another laser, etc.) 1.2.4 In practice, it is very difficult to obtain a Optical cavity (typically bound by reflectors to act population inversion when utilizing only one excited as the feedback mechanism for light amplification) energy level. Electrons in this situation have a tendency todecay to their ground state very quickly. As shown in 1.2.2 Electrons in the atoms of the lasing medium Figure 1-3, a lasing medium typically has at least one normally reside in a steady-state lower energy level. When excited (metastable) state where electrons can be trapped energy from a pump source is added to the atoms of the long enough (microseconds to milliseconds) to maintain a lasing medium, the majority of the electrons are excited to population inversion so that lasing can occur. Although a higher energy level, a phenomenon known as population laser action is possible with only two energy levels, most inversion. This phenomenon must occur in order to achieve lasers have four or more levels. 1.2.3 The excited state is an unstable condition for 1.3 TYPES OF LASERS
these electrons. They will stay in this state for a short timeand then decay back to their original energy state. This 1.3.1 There are a number of methods used in decay can occur in two ways — spontaneously or by producing laser energy. Common methods include the use stimulation. If, before an excited electron spontaneously of semiconductors, liquid dye, solid state, gas and metal decays, it is hit with a photon with a certain wavelength, vapour. Although the technology behind each type can be the electron will be stimulated into decay and will emit a quite different, the resulting laser energy has the same basic photon of the same wavelength and in the same direction as characteristics (see Table 1-1).
the incident photon. If the direction of this reaction isparallel to the optical axis of the cavity, the emitted photons 1.3.2 In recent years, the semiconductor laser (laser travel back and forth in the cavity stimulating more and diode) has become the most prevalent laser type. The laser more transitions and releasing more and more photons all diode is a light emitting diode (LED) with an optical cavity in the same direction and with the same wavelength. The to amplify the light emitted from the energy band gap that light energy is therefore amplified. Since one of the mirrors exists in semiconductors.
Optical cavity Figure 1-2. Diagram of solid state laser
Chapter 1. Physics of lasers Table 1-1. Examples of common lasers
Lasing medium Laser method Spectral region Frequency-doubled Nd:YAG Gallium aluminium arsenide Visible – near IR Titanium sapphire Manual on laser emitters and flight safety 1.3.3 Lasers can operate continuously (continuous given period of time (such as a single laser pulse). Power wave or CW) or may produce pulses of laser energy. Pulsed is typically given in watts (W) and energy is typically given laser systems are often repetitively pulsed. The pulse rate or in joules (J). They are mathematically related as follows: pulse repetition frequency (PRF) as well as pulse durationand peak power are extremely important in evaluating potential biological hazards. Due to damage mechanisms in biological tissue, repetitively pulsed lasers can often bemore hazardous than a CW laser with the same averagepower.
Irradiance and radiant exposure
1.4.3 With the exception of what is absorbed by the 1.4 BEAM PROPERTIES
atmosphere, the amount of energy available at the output ofthe laser will be the same amount of energy containedwithin the beam at any point downrange. Figure 1-4 Laser output intensity
illustrates a typical laser beam with a sampling area smallerthan the cross-sectional area of the beam. The amount of 1.4.1 Lasers either emit continuously or produce energy available within the sampling area will be discrete pulses of optical radiation. When dealing with considerably less than the amount of energy available continuous wave (CW) lasers, beam power is used. Beam within the total beam. Irradiance describes the power per energy is used for single pulse lasers. However, when unit area, and radiant exposure describes the energy per dealing with repetitively pulsed lasers, either parameter can unit area of a laser beam.
be used. Care must be taken to ensure that the correctparameter is considered when comparisons with safetythresholds are made.
Laser modes (laser power distribution)
1.4.2 Laser power is the rate with which laser energy 1.4.4 Laser beams can have complex patterns and is emitted. This means that at any given instant, a laser can shapes. The optical power distribution within a laser beam produce a certain quantity of laser power. Laser energy is a (called the laser mode) is typically expressed with either a measure of the amount of optical radiation received in a single bell-shaped (Gaussian) power density profile or a Excited energy level Metastable energy level Stimulated emission Ground energy level Figure 1-3. Diagram of three-level laser energy
Chapter 1. Physics of lasers combination of multiple bell-shaped profiles. A uniform manufacturers will specify their laser beam diameters (constant) power mode is actually a combination of many assuming an aperture that blocks 13.5 per cent (1/e2) of the Gaussian profiles overlapping each other. The ideal laser is output (allowing 86.5 per cent to pass). The 1/e beam considered to have a single Gaussian profile for most laser diameter is equal to the 1/e2 beam diameter divided by the applications. This mode is often assumed in order to square root of 2 (i.e. 1.414).
simplify laser hazards analyses.
1.4.5 Since a Gaussian distribution has no mathematical beginning or ending (see Figure 1-5), defining Line width
the diameter of a laser beam can be difficult. To solve thisproblem, one can define the diameter of a laser beam by 1.4.6 Light from a conventional light source is determining the diameter of an aperture that would allow extremely broadband (containing wavelengths across the only a certain percentage of the total beam output to pass electromagnetic spectrum). If one were to place a filter that through. The 1/e beam diameter is defined as the size of an would pass only a very narrow band of wavelengths (e.g. a aperture that would block 36.8 per cent (1/e) of the beam green filter) in front of a white or broadband light source, output (allowing 63.2 per cent to pass). This is the method only that colour or wavelength region would be seen most often used for laser safety evaluations. Some laser exiting the filter (see Figure 1-6).
Figure 1-4. Illustration of irradiance
Intensity Distance Figure 1-5. Beam diameter

Manual on laser emitters and flight safety 1.4.7 Light from the laser is similar to the light seen function of range, r, from the exit port or beam waist and from the filter. However, instead of a narrow band of can be calculated as: wavelengths, none of which is dominant as in the case ofthe filter, there is a much narrower bandwidth about a DL = a2 r2ϕ2 dominant centre frequency emitted from the laser. Thecolour or wavelength of light being emitted depends on the where a is the 1/e beam diameter at the exit port or beam type of lasing material being used. For example, if a neodymium:yttrium aluminium garnet (Nd:YAG) crystal isused as the lasing material, light with a wavelength of1 064 nm will be emitted. Certain materials and gases arecapable of emitting more than one wavelength. The wave- 1.5 CHARACTERISTICS OF MATERIALS
length of the light emitted in such a case is dependent onthe optical configuration of the laser.
1.5.1 Materials can reflect, absorb and transmit light rays. Reflection of light is best illustrated by a mirror. If 1.4.8 Light from a conventional light source diverges light rays strike a mirror, almost all of the energy incident (spreads rapidly) as illustrated in Figure 1-7. The power or on the mirror will be reflected. Figure 1-10 illustrates how energy per unit area may be large at the source, but it a plastic or glass surface will act on an incident light ray.
decreases rapidly as an observer moves away from the The sum of energy transmitted, absorbed and reflected will source. In contrast, the output of the laser shown in equal the amount of energy incident upon the surface.
Figure 1-8 has a very small divergence and the beam ir-radiance or radiant exposure at shorter distances is almost 1.5.2 A surface is specular (mirror-like) if the size of the same at the observer as at the source. Thus, within a surface imperfections and variations are much smaller than narrow beam, relatively low-power lasers are able to the wavelength of incident optical radiation. When project more energy than can be obtained from much more irregularities are randomly oriented and are much larger powerful conventional light sources.
than the wavelength, then the surface is considered diffuse.
In the intermediate region, it is sometimes necessary to 1.4.9 The divergence, ϕ, of a laser beam used in laser regard the diffuse and specular components separately.
safety calculations is defined as the full angle of the beamspread measured between those points which include laser 1.5.3 A flat specular surface will not change the energy or irradiance equal to 1/e of the maximum value. As divergence of the incident light beam significantly. Curved a laser beam propagates through space, it produces a profile specular surfaces, however, will change the beam as shown in Figure 1-9. The beam diameter, DL, is a divergence. The amount that the divergence is changed is "Line filter" with Figure 1-6. Laser line width
Chapter 1. Physics of lasers dependent on the curvature of the surface. Figure 1-11 laser beam. A surface that would be a diffuse reflector for demonstrates these two types of surfaces and how they will a visible laser beam might be a specular reflector for an IR reflect an incident laser beam. The divergence and the laser beam. As illustrated in Figure 1-12, the effect of curvature of the reflector have been exaggerated to better various curvatures of diffuse reflectors makes little illustrate the effects. The value of irradiance measured at a difference on the reflected beam. The phenomenon known specific range from the reflector will be less after reflection as scatter is the diffuse reflection from very small particles from the curved surface than after reflection from the flat surface, unless the curved reflector focuses the beam nearor at that range.
1.5.4 A diffuse surface will reflect the incident laser beam in all possible directions. The beam path is not 1.5.5 Refraction is the deflection of a ray of light maintained when the laser beam strikes a diffuse reflector.
when it passes from one medium into another. If light is Whether a surface is a diffuse reflector or a specular incident upon an interface separating two transmitting reflector will depend upon the wavelength of the incident media (such as an air-glass interface), some light will be Figure 1-7. Divergence of conventional light beam
Figure 1-8. Divergence of laser beam
Manual on laser emitters and flight safety transmitted while some will be reflected from the surface.
absorption and scattering. After propagating a distance, r, If no energy is absorbed at the interface, T + R = 1.00 through the atmosphere, intensity, I, is given by: where T and R are the fractions of the incident beamintensity that are transmitted and reflected. T and R are I = I0e–µr called the transmission and reflection coefficients,respectively. These coefficients depend not only upon the where I0 is the initial intensity and µ is the atmospheric properties of the material and the wavelength of the attenuation coefficient. The units of µ must be the inverse radiation but also upon the angle of incidence.
to that of r, that is, if r is represented in cm, then µ mustbe represented in cm–1 so that the term µr is dimensionless.
1.5.6 The angle that an incident ray of radiation forms with the normal (perpendicular) to the surface will 1.5.9 This equation shows that the intensity falls off determine the angle of refraction and the angle of reflection exponentially as a function of the distance from the laser (the angle of reflection equals the angle of incidence). The source. The attenuation coefficient is dependent on the relationship between the angle of incidence (θ) and the wavelength of the laser. Because of the combination of angle of refraction (θ') is: absorption and scattering effects, the attenuation coefficientis a complex function of wavelength having a large value at n sin (θ) = n' sin (θ') some wavelengths and a small value at others.
where n and n' are the indices of refraction of the mediathat the incident and transmitted rays move through, respectively (see Figure 1-10).
1.5.10 Scintillation is caused by random variations in 1.5.7 Since refraction can change the irradiance or the index of refraction of the atmosphere through which the radiant exposure, it can either increase or reduce a laser beam is passing. These index variations are caused by localized temperature and pressure fluctuations. This resultsin a focusing effect which creates hot spots in the beam pattern, most pronounced at long ranges. Scintillation of alaser beam creates a flickering pattern of light similar to 1.5.8 As light propagates through the atmosphere or what one might expect at the bottom of a swimming pool any medium, its total power or energy is attenuated by when the water surface is not calm and the sun shines into it.
Figure 1-9. Geometry of laser beam
Chapter 1. Physics of lasers Figure 1-10. Light ray incident to a glass surface
Figure 1-11. Specular reflectors
Manual on laser emitters and flight safety Figure 1-12. Diffuse reflectors
Chapter 2
is of relatively low power (e.g. 5 milliwatt) and theobserver is at a considerable distance from the source. In The purpose of a laser hazard evaluation is to minimize the this context, the focusing ability of the eye is very potential for injury to personnel from a laser emitter. As important. Laser light passing through a pupil of 7 mm part of this evaluation, the accessible emission limit (AEL), diameter can be focused into a spot on the retina only 2–20 laser classification, nominal ocular hazard distance µm big. It can be calculated that the irradiance of (NOHD) and optical density (OD) required for personnel collimated light is increased up to 100 000 times from the protection are determined. In addition, engineering and cornea to the retina.
administrative control measures should be considered.
The AEL is defined as the maximum accessible The retina is especially sensitive to laser light emission power or energy permitted within a particular beams for two reasons: class. The class 1 AEL is the value to which laser outputparameters are compared. The class 1 AEL is calculated by a) irradiance from a conventional source, such as a multiplying the maximum permissible exposure (MPE) by light bulb, is reduced with increasing distance from the area of the limiting aperture.
the source according to the inverse square law, i.e.
the irradiance is reduced as a function of the squareof the distance from the source. Since a laser beam Maximum permissible exposure (MPE)
is collimated, it does not follow the inverse squarelaw and its irradiance for a given power output is The MPE is a function of wavelength, exposure usually far greater at a given distance than that from time and the nature of exposure (intrabeam, diffuse a conventional light source; and reflection, eye or skin). MPE values are determined frombiological studies and are published in regional, national b) if light from a conventional source is focused by (e.g. American National Standards Institute ANSI Z136.1) means of a reflecting surface, as in a searchlight, and international (e.g. International Electrotechnical the irradiance downrange of the source is greater Commission IEC 60825-1) laser safety standards.
than would be expected according to the inversesquare law. However, it is not possible to collimate MPE values are expressed in terms of irradiance conventional light energy. For a given power or radiant exposure and are given in W/cm2 or J/cm2 (W/m2 output, a conventional light source cannot, or J/m2). They represent the maximum levels to which a therefore, produce a light beam which has an person can safely be exposed without incurring biological irradiance similar to that of a laser beam.
damage. However, sub-damage threshold effects may besignificant at exposure levels below the MPE.
Collimated light rays reaching the eye are focused by the cornea and lens onto a very small area of theretina similar to the way parallel light rays from the sun can Limiting aperture (Df)
be focused by a magnifying glass into a spot of sufficientirradiance to burn paper. A laser beam can have an The limiting aperture (Df) is the maximum irradiance which exceeds that of the sun, even if the laser diameter of a circle over which irradiance or radiant Manual on laser emitters and flight safety exposure can be averaged. It is a function of wavelength Class 2 lasers
and exposure duration. These values are provided innational and international laser safety standards. The Class 2 lasers are low-power visible (400 to limiting aperture is a linear measurement and is thus 700-nm wavelength) lasers and laser systems that can emit expressed in terms of cm or mm.
an accessible output exceeding the class 1 limits but notexceeding the class 1 AEL for a 0.25 second exposure The MPE for eye exposure in the 400 to 1 400 duration. The class 1 AEL for a 0.25 second exposure nm band (retinal hazard region) is based upon the total duration is 1 mW. Invisible lasers cannot be class 2.
energy or power collected by the night-adapted human eye,which is assumed to have an entrance aperture of 7 mm indiameter. This diameter is the limiting aperture. Todetermine the potential hazard, the maximum energy or Class 3 lasers
power that can be transmitted through this aperture must bedetermined. This amount is compared to the class 1 AEL.
Class 3 is subdivided into 3a and 3b (3A and 3B For lasers with wavelengths outside the retinal hazard region in international standards). Class 3a lasers are medium- and for the skin, other limiting apertures may apply (see power lasers with an output between 1 and 5 times the applicable national or international standards).
class 1 AEL (class 2 AEL for visible lasers) based on theappropriate exposure duration. All other lasers at anywavelength not classified as class 1 or class 2 with a powerless than 500 mW and unable to produce more than 125 mJ LASER HAZARD CLASSIFICATION
in 0.25 seconds are defined as class 3b (3B). The Inter-national Electrotechnical Commission (IEC) international Laser hazard classifications are used to indicate standard also has a limit on irradiance for class 3A lasers the level of laser radiation hazard inherent in a laser system of 25 Wm–2 (2.5 mW cm–2).
and the extent of safety controls required. These range fromclass 1 lasers, which are safe for direct beam viewing undermost conditions, to class 4 lasers, which require the moststrict controls.
Class 4 lasers
Class 4 lasers are high-power lasers including Classification is based only on unaided and all lasers in excess of class 3 limitations. These lasers can 5-cm-aided viewing conditions. This means that the power often be fire hazards. Both specular and diffuse reflections or energy that can pass through the limiting aperture are likely to be hazardous.
(known as the effective power or energy) is compared to theappropriate AEL when determining hazard classification.
The laser classification system is summarized below (for afull description, reference should be made to the applicable national or international standards).
The NOHD is the maximum range at which the Class 1 lasers
power or energy entering the limiting aperture can exceedthe class 1 AEL. This value expresses the minimum safe Class 1 lasers are lasers which cannot emit distance from which a person can directly view a laser radiation in excess of the class 1 AEL (based on the source without a biological damage hazard. The class 1 maximum possible duration inherent in the design or AEL is calculated by multiplying the MPE by the area of a intended use of the laser) or which have adequate circle with a diameter of the limiting aperture (Df).
engineering controls to restrict access to the laser radiationfrom an embedded higher class of laser. This does not, MPE ⋅ π ⋅ D however, necessarily mean that the system is incapable of AEL = MPE × π = ----------------- doing harm. Since only unaided and 5-cm-aided viewingconditions are considered, hazards may still be posed whenviewing optics with a greater optical gain than 7.14 (5-cm The following equation describes the optics) are used or if access to the interior of the laser relationship between energy through a limiting aperture, Qf, emitter is possible.
(effective energy) to total energy, Qo, of a Gaussian laser Chapter 2. Laser hazard evaluation beam, given the 1/e beam diameter, DL, the aperture those viewing conditions are possible. However, the diameter, Df, and neglecting atmospheric losses.
maximum OD will never be more than: This equation assumes that all laser energy is concentrated into the limiting aperture with no transmissionloss through optics. This is the worst case condition.
When including the effects of divergence, at- mospheric attenuation and viewing aids (see 1.4.9, 1.5.8 to1.5.10 and 3.7.7, respectively, for further explanation), thisequation becomes: In performing a laser hazard evaluation, other G D – ------------------ issues must be considered. Things such as critical task –µ ⋅ r 1 – e  + Q ⋅ τ ⋅ e impairment, properly working safety interlocks, standardoperating procedures, and signs and labels are integral where G represents the effective optical gain and τ factors in establishing a safe environment for laser represents the transmission of viewing aids.
operation. The significance of specific control measuresdepends upon the laser hazard classification. A start-up If the class 1 AEL (the maximum safe level of delay, for example, should not be necessary for a class 2 exposure) is substituted for Qf (the actual exposure that laser device. Applicable national or international laser could be received), the range, r, becomes the NOHD.
safety standards list the control measures required for each Making these substitutions and solving for NOHD results in laser hazard class.
Buffer zones
D × G -------------------------------- – a 1n1 – ---------------------  With outdoor lasers, a buffer zone should be –µ ⋅ NOHDQ ⋅ τ ⋅ e established and utilized for each laser system. A bufferzone is a conical volume centered on the laser's line ofsight with its apex at the laser aperture using a specifiedbuffer angle. Within the buffer zone, the beam will be OPTICAL DENSITY (OD)
contained with a very high degree of certainty. The lasersystem's buffer zone depends on the aiming accuracy and Since some lasers or laser systems may produce boresight retention of the laser system. Typically, the laser energy or power millions of times that of the class 1 AEL, system's buffer zone is equal to five times the system's the use of logarithms is the preferred method to express aiming accuracy. The typical buffer angles for lasers used personnel protection requirements. To fully specify the eye outdoors are 10 mrad for hand-held lasers and 5 mrad for protection requirements for a particular laser system, lasers on a stable platform. unaided and aided OD values are calculated.
To determine the OD of eyewear required to Nominal hazard zone (NHZ)
protect personnel from incident laser radiation, the ratio ofthe effective energy, Qf, to the class 1 AEL is used as The volume of space defined by all locations capable of exceeding the class 1 AEL (including the bufferzone) is known as the nominal hazard zone (NHZ). Anyone outside the NHZ is considered to be safe from laser 10  AEL hazards. Anyone within the NHZ should be protected byeither procedural safeguards or personnel protection To consider the effects of binoculars or other equipment (e.g. laser safety goggles). Small specular viewing aids, the change in the effective energy will reflectors in the laser beam path can create unwanted beams produce different OD values and must be considered if and should be considered in determining the NHZ.
Manual on laser emitters and flight safety Laser-beam sensitive, laser-beam critical and
2.7.4 are substituted for the appropriate MPE, new AEL laser-beam free flight zones
values are determined, and the range is recalculated. Notethat these values are only relevant to visible laser beams.
Biologically safe exposure of the eye to a visible These values have no meaning for wavelengths outside the laser beam can create unwanted effects that can reduce or visible spectrum (400–700 nm).
destroy the ability of a person to perform a task. Theseeffects can be very hazardous if the task is safety-critical (e.g. landing an aircraft). Three visual interference levelshave been defined and are described in 2.7.5 and in greater Although laser radiation is the most obvious detail in 3.8. These values are as follows: hazard associated with laser systems, many other hazardsshould be considered in a laser hazard evaluation. These are sensitive level — 100 µW/cm2 known as non-beam hazards. The following list shows critical level — 5 µW/cm2 several non-beam hazards common to laser use: laser beam free level — 50 nW/cm2 collateral radiation The sensitive level approximates the level at compressed gases which a person could experience severe, lingering after- effects from exposure to a laser beam. The critical level approximates the level to which a person could experience significant loss of vision during exposure to a laser beam and some residual, lingering after-effects. The laser beam free level approximates the level at which a person would receive a distracting glare but no after-effects. The laser beam sensitive, critical and free flight zones are the respective volumes of space where levels above these are Determining the distances associated with these trailing cables/pipes visual interference levels is done the same way as when evaluating the NOHD values. The values mentioned in Chapter 3
Therefore, this chapter will only serve to be an overview ofparticular aspects of those effects, namely their bioeffects 3.1.1 The development of the laser and the industrial and how they relate to aircraft operations. Other technical application of laser technology stand out as some of the publications exist that cover this topic more compre- most significant scientific contributions of the 20th century.
hensively, some of which are listed in the bibliography at Presently, lasers are found virtually everywhere, from the end of this chapter.
supermarkets and schools to satellites and operating rooms,and have become fundamental components in consumer 3.1.4 Depending on power and other physical products and complex industrial devices, including characteristics, laser beams have the potential to generate a sophisticated weapon systems. The accessibility of the variety of bioeffects, including the capacity to vapourize technology and the significant reduction in cost place lasers biological tissue, either in part or in full, sometimes at almost everyone's disposal. Furthermore, the application destroying the entire organism. This chapter, however, will of laser technology to modern society is still emerging and be limited to those laser beam bioeffects likely to be its future potential appears boundless.
encountered within civilian aircraft operations and pri-marily those affecting the skin and the eye. The major part 3.1.2 However, if used improperly, laser energy also of this chapter will address this risk from the perspective of poses a significant biohazard. Consequently, even the most its potential effect on vision, since this is the primary innocuous laser pointer can become a safety hazard, either through direct bioeffects or by causing a disruption ofcritical performance tasks in hazardous situations.
3.1.3 Not surprisingly, as lasers proliferate, an ever- increasing number of laser beam-related incidents, some 3.2.1 The spectrum of electromagnetic radiation from misadventure and others caused by intentional misuse, ranges from the shortest of cosmic rays at 10–5 nm to very have been reported. A significant number of these incidents long waves in the order of 1014 nm (100 km), as associated involve aircraft operations, both civil and military. Low- with communications and power sources. Each of these flying helicopters, as used by police and for medical wavelengths is associated with photons of varying energy.
evacuation, are particularly vulnerable, not only because of The shorter the wavelength, the higher the energy asso- their proximity to the ground but also because of their ciated with the photons at that specific wavelength. For proximity to ground-based lasers. In some aviation tissue interactions at the atomic level, the higher the level environments, even the most trivial of laser beams have the of energy associated with these photons, the higher the risk potential to become a lethal threat, e.g. by distraction of for biological effects. Therefore, radiation of shorter aircrew during a critical phase of flight. This chapter will wavelengths has the greatest potential to be biologically elaborate on the bioeffects and damage mechanisms of laser beam energy particularly from the perspective of itseffects on aircraft operations. However, the ongoingdevelopment of new lasers and the continued advances in 3.2.2 The sun is the source for most of the natural research associated with lasers and their effects make this electromagnetic radiation reaching the earth. Fortunately, a vast and still evolving area of biological science.
the atmosphere protects the surface of the planet from many Manual on laser emitters and flight safety of these wavelengths and their associated hazards, but a Table 3-1. Optical radiation spectral bands
significant portion of the electromagnetic spectrum stillpenetrates this protective barrier to become an en- vironmental biohazard. In addition, industrial sources cancreate hazardous radiation in any environment. 3.2.3 The optical radiation portion of the electromagnetic spectrum can interact with the human eye and skin. Optical radiation extends from the shortest ultraviolet wavelength, at 100 nm, through the visible 3 000–1 000 000 spectrum up to and including longer IR wavelengths around1 mm (106 nm), such as those associated with radar. The * Although the visible range can be regarded to extend beyond optical radiation portion of the electromagnetic spectrum 700 nm, usually up to 770 nm or even higher in some in- can be a biohazard when associated with visible and dividuals, by convention and to maintain consistency with invisible laser beams.
other accepted international standards, the visible range will belimited to 400–700 nm in this manual.
3.2.4 The International Commission on Illumination (CIE) has divided the optical radiation portion of the 3.3.2 In order for biological damage to occur, a spectrum into the bands listed in Table 3-1, which include molecule must absorb the photons emitted by the radiation IR, visible (VIS) and UV wavelengths: source. The Grotthus-Draper Law states that photons mustbe absorbed by a molecule before a photochemical effectcan occur. The Stark-Einstein Law states that only one 3.2.5 The atmospheric contents normally shield the photon has to be absorbed by a molecule to cause an effect.
surface of the planet from UVC radiation. Wavelengths If a photon is absorbed, then biological damage may occur below 180 nm are completely blocked by the atmosphere.
as a consequence of one of three main damage mechanisms Without this protection, biological life on the planet would or any combination thereof: photochemical (photolytic),
not be possible. Although not a naturally occurring thermal (photocoagulative) and acoustico-mechanical.
biological threat, any of these wavelengths can beartificially generated and exploited by means of laser-based 3.3.3 Within any given biological tissue, the amount of damage that occurs represents a summation of all thesemechanisms as well as other propagated local tissue effects;therefore, tissue damage will usually extend beyond theimmediate confines of individual molecular locations. In 3.3 BIOLOGICAL TISSUE
some cases, tissue damage can be induced at a considerable distance from the location of the absorbing molecules,e.g. from oedema or vascular disruption.
3.3.1 In order for phototoxic damage to occur in a biological tissue, radiation must be absorbed by somemolecular constituent of that biological tissue. If the radiation passes through the tissue without molecularabsorption, no biological damage occurs. However, most 3.3.4 Photochemical (photolytic) damage occurs molecules have the ability to absorb at least some portion when the energy of an incoming photon is high enough to of the electromagnetic spectrum. It is possible to plot, for break (lyse) existing chemical bonds within individual any given tissue, those ranges of radiation (wavelengths) to molecules. The effect of this is to alter or destroy the which that individual tissue is sensitive. That tissue plot absorbing molecules and to transform them into unwanted represents a summation of the individual sensitivities of all free radicals. A considerable amount of research and of its constituent molecules and is known as the action interest continues regarding the acute and chronic tissue spectrum. In many cases, the action spectra of different effects from the generation of free radicals, regardless of individual tissues have been precisely calculated and they cause. A large portion of an organism's ability to resist the are associated with very specific wavelengths. Most action long-term consequences of tissue-free radicals that are spectra have been well described for the different tissue generated on a daily basis involves many chemical types. A classic example of this is the action spectrum for mediators that repair this damage and remove these free photokeratitis (inflammation of the cornea), which is radicals from individual tissues in order to neutralize their related to excessive ultraviolet exposure (see Figure 3-1).
potential negative effects. When these damage repair Chapter 3. Laser beam bioeffects and their hazards to flight operations mechanisms or mediators cannot compensate for the rate of into one of several types of unstable excited states, the most free-radical generation, many acute and chronic diseases unstable of which is often referred to as a triplet state.
are known to follow. Examples of these include cataracts, These states are very unstable. The newly acquired level of macular degeneration, corneal degenerations and a variety excess energy is usually shed quickly and these states, of degenerative skin conditions, from loss of elasticity therefore, are of extremely short duration. In some cases, (wrinkles) to skin cancers.
the release of energy occurs visibly by re-radiation of theenergy as light at another wavelength, either as 3.3.5 The shorter the wavelength, the higher the phosphorescence or fluorescence. Generally, however, this energy associated with those particular photons. High- energy is released as an exothermic reaction by giving off energy photons, for example UVC, have sufficient energy heat. Depending on the amount of heat generated and the to break carbon-to-carbon bonds, which are some of the thermal sensitivity of the surrounding tissues, if normal strongest biochemical bonds in living tissue. This is why thermal dissipating mechanisms fail to compensate or are atmospheric UVC absorbers, such as oxygen, ozone, water, overloaded, this thermal process will then induce thermal carbon dioxide and other atmospheric constituents, are damage. The heat can damage surrounding proteins and critically linked to human survival on earth. Thus, it is the other tissues well beyond the immediate surrounds of the energy associated with these shorter UV wavelengths that absorbing molecules. This explains why the visual effects accounts for a significant portion of the photochemical of a retinal burn from a laser beam can be much larger than damage seen in both the skin and the eye. In fact, expected from the size of the visible retinal lesion. wavelengths shorter than 320 nm are regarded as the activeactinic ultraviolet range. Lasers can provide a concentratedsource of photons at virtually any wavelength and thus are quite efficient at causing photochemical damage, eitherfrom low-intensity long exposures or high-intensity short 3.3.7 Acoustico-mechanical damage occurs as a consequence of high energy, short-duration exposures tolaser beams. This damage mechanism consists of severalsub-processes. These include acoustic shock waves induced by the impact of the laser beam itself and severalconsequences thereof. For example, ultra-fast elevations of 3.3.6 When an inorganic or organic molecule absorbs tissue temperature can generate steam bubbles in the tissue.
a photon, this additional new energy drives the molecule Mechanically, this can either destroy surrounding tissue as Wavelength in nanometres (nm) Figure 3-1. Action spectrum for photokeratitis
Manual on laser emitters and flight safety a function of being a space-occupying lesion or by inducing 3.3.11 The individual sensitivity of any biological additional shock waves, which then propagate into and tissue to any given radiation can be artificially increased through various neighbouring tissues inducing even further (damage threshold decreased) by the use of certain structural damage. In addition, the ability of radiation to photosensitizing agents or medications. There is a large and create a highly ionized state of matter (plasma) in growing list of assorted pharmaceutical agents, both topical combination with this steam-generating process can result and systemic, that can make an individual more vulnerable in a cavitation process with formation of bubbles that can to biological damage in some tissues in any given setting.
further disrupt delicate tissue structures. Such effects can be In some cases, this can elevate tissue sensitivity to such a very dramatic and may affect areas up to 200 times larger degree that a known non-damaging level of a particular than the thermal damage area. This cavitation process, also radiation can suddenly and unexpectedly become a called an optical breakdown, can be used quite effectively, significant biohazard. A list of some common photo- e.g. by a Nd:YAG laser, to create mechanical disruption of sensitizers is provided in Table 3-2.
tissue. This effect is used clinically by ophthalmologists tocut through opacifications of the posterior capsule of thelens (capsulotomy) which may form after extracapsular lensextraction, to lyse tissue bands deeper in the eye and tocreate holes in the iris (iridotomy) to treat angle closure 3.4 THE SKIN
3.4.1 The wavelength sensitivity range of the skin and 3.3.8 The types of bioeffects and related tissue the eye to optical radiation are generally very similar.
damage induced by a laser beam in either the skin or the While the likelihood of a skin injury is statistically higher eye are dependent on many variables, including the because the skin has a much larger vulnerable surface area physical characteristics of the laser emitter itself, the than the eye, the actual operational consequences of such environmental setting and the biological characteristics of skin effects are generally trivial. Furthermore, this the target tissue and its surrounding structures.
vulnerability of the skin can easily be diminished by simpleprotective measures, such as covering the exposed areaswith garments or chemical blocking agents. Nonetheless, 3.3.9 The physical characteristics related to the laser when exposed to optical radiation, the skin can suffer the emitter itself are discussed in depth in Chapter 1. The most consequences, both acute and chronic, of all three biological tissue-damage mechanisms. The typical acuteskin injury is likely to be a surface burn that may be severe enough to require medical management. Cumulative effects initial beam size manifest themselves later in life as chronic conditions, such power and power density as wrinkles, skin folds (e.g. cutis rhomboidalis nuchae) and skin cancers. It is estimated that 80 per cent of the lifetime output mode (pulsed or CW) carcinogenic exposure to UV radiation occurs before age pulse properties (PRF, pulse width, etc.) 21. Proper UV protection should be diligently followedfrom the earliest possible age; especially important is theprotection of infants.
3.3.10 The ability of any given laser beam to induce bioeffects and generate damage can be tempered orenhanced by environmental factors. This is particularly 3.4.2 It is possible to disrupt skin and entire germane with respect to the eye. Such environmental organisms with more powerful lasers such as those developed for military, industrial and scientific use. It is,however, unlikely that acute skin damage from a laserbeam will disable aircrew, either physically or ambient luminance (which determines the level of psychologically, and thus play a role in the disruption of light adaptation) safe air operations. Additional information is available in distance from laser source technical publications dealing with induced skin damage.
atmospheric conditions Unnecessary exposure to radiation, particularly UV, should angle of incidence be avoided to reduce potential toxic cutaneous effects, both intervening optical interfaces acute and chronic. The amount of UV radiation increases viewing conditions (unaided or with magnification with altitude, as a general rule increasing three to four per cent for every 300 m (1 000 ft) gain in altitude.
Chapter 3. Laser beam bioeffects and their hazards to flight operations Table 3-2. Common photosensitizing agents
3.5.4 This absorption process induces changes within the lens, such as yellowing, which make it a more effectiveblue-wavelength and UV filter. But the absorption may also result in increasing opacification of the lens in the form of nuclear and cortical sclerosis (senile cataract) that eventually disrupts overall visual performance. Once the lens is removed surgically, this normal barrier to UV radiation is also removed and thus retinal tissue is now exposed to higher levels of UV that normally would have been absorbed by the natural lens. This necessitates additional sun protection even in individuals with im- planted intraocular lenses (IOL) containing UV radiation- Porphyrins (porphyria) absorbing additives because such lenses do not reliably protect the retina against UV radiation.
Sulfonylurea Tretinoin (retinoic acid, vitamin A acid, Retin-A®) 3.5.5 The characteristics of each ocular tissue with respect to optical radiation will now be discussed in moredetail. Figure 3-2 is provided to facilitate the discussion.
The cornea
3.5.1 It is the acute disruption in visual performance 3.5.6 The multi-layered cornea is a clear ocular and the potential of laser beams to induce ocular damage that structure, which contributes the bulk of the light-bending are of paramount importance to aircrew in the performance power (refractive power) of the eye as it naturally focuses of their duties and which implies a threat to flight safety. incoming light rays on the retina. The cornea can absorbvirtually 100 per cent of UV wavelengths shorter than280 nm (UVC). This is usually of little importance as the 3.5.2 Optical radiation can be divided into two atmosphere already absorbs almost all of the natural UVC, general regions with respect to the potential of a laser beam even at the highest flight levels. Artificial sources that to cause damage: the retinal hazard region and the non- generate UVC within the environment are a different retinal hazard region. The wavelengths of the retinal hazard matter. The overall absorption of the UV radiation band by region include the visible and near infrared (NIR) band and the cornea decreases as the wavelength increases, so that represent those wavelengths that are transmitted through more and more UV radiation is gradually passed on the optical media of the eye (cornea, aqueous humour, lens through the aqueous humour to the lens. At 360 nm, the and vitreous body) and are focused on the retina. This band cornea absorbs about 34 per cent of the UV radiation. On includes the entire visible range between 400 and 700 nm, the other hand, the cornea absorbs very little of the visible up to the end of the near infrared (IR-A) range at 1 400 nm.
and NIR portions of the spectrum, passing over 95 per centof this range on to the retina as a more concentrated or 3.5.3 The non-retinal hazard region refers to those focused beam.
wavelengths that are mostly absorbed by anterior oculartissues (cornea and lens) without significant transmission 3.5.7 Absorption of excessive UV radiation by the posteriorly to the retina. This band includes UV and the cornea can cause corneal tissue damage as a function of its longer IR bands, those greater than 1 400 nm (IR-B and action spectrum. The classic example of this is photo- IR-C). Although some of the non-retinal hazard radiation keratitis associated with arc-welding, artificial suntanning can be transmitted through some ocular tissues, almost all or exposures to high levels of environmental UV radiation, of it is normally absorbed before it reaches the retina. This such as that typical of snow and water activities. UV absorption process, however, can also have acute and radiation has also been identified as causing several types chronic effects on the absorbing tissues themselves, of corneal degeneration often referred to as climatic droplet especially if normal repair capabilities are exceeded. The keratopathies, such as Bietti's corneal degeneration and classical example of this is the crystalline lens, which is the Labrador Keratopathy. Damage repair mechanisms and the final tissue barrier to UV radiation. It absorbs virtually all replicating nature of the corneal epithelium generally limit of the residual UV radiation that passes through the cornea such effects to only a temporary condition, albeit an and the aqueous humour.
extremely painful one. Such exposures can be epidemic as Manual on laser emitters and flight safety described by Xenophon in Anabasis where large multitudes heat and other damage effects is very limited, a factor of Greek soldiers at altitude were incapacitated by "solar which ultimately contributes to cataract formation later in blindness" during an organized military retreat. However, life. The lens transmits visible and near IR radiation with very high-intensity laser beams, it is possible to induce virtually unattenuated but with some scatter. However, the stromal damage deep in the cornea. This would cause lens will absorb mid-infrared energy (IRB) such that it is formation of a permanent corneal scar with the potential possible to induce lenticular damage with levels of IR loss of vision depending on its location. Fortunately, such energy that are not high enough to induce corneal damage.
powerful UV radiation laser emitters are not readily The lens will also absorb increasing amounts of short, visible wavelengths (violet and blue) as it yellows with age.
3.5.8 UV radiation-induced corneal injury is usually superficial, temporary and reversible. Nonetheless, it can be The vitreous humour
very disabling and painful. A severe acute corneal lesioncould render aircrew visually incapacitated.
3.5.12 The vitreous humour or vitreous body (corpus vitreum) is an optically clear structure composed ofgelatinous and aqueous material with few structural fibres The aqueous humour
and cells. It does, however, have some very limited abilityto absorb UV radiation and by design passes visible and 3.5.9 The aqueous humour is a transparent fluid with NIR radiation to the retina virtually without attenuation.
very few floating cellular elements. It does, however,absorb some of the UV radiation that gets through thecornea but not in any appreciable quantities. Similarly, it The retina
passes IR and visible radiation virtually unattenuatedthrough to the lens.
3.5.13 The retina contains the neural elements and photoreceptors (rods and cones) of the visual system and itis the prime concern with respect to phototoxic damage induced by any optical radiation. 3.5.10 The crystalline lens provides the final focusing element of the optical structures of the eye. While it provides 3.5.14 Retinal susceptibility to photolytic damage substantially less refractive power than the cornea, it is the increases as the wavelength decreases. Furthermore, the only dynamic focusing element with the ability to refine the absorption of the retinal pigment epithelium is higher in the final focus on the retina. It does so automatically and almost near UV range than in the visible range. Therefore, thermal instantaneously. It is also, essentially, the last tissue barrier to retinal damage can occur if UV reaches the retina in any of the UV radiation that penetrates the cornea and significant amounts. While normally protected from UV by aqueous humour. The lens absorbs increasing amounts of the anterior segment of the eye, the retina is vulnerable to UV radiation above 300 nm (UVB), such that it absorbs UV exposure, especially from 320 nm radiation. The retinal approximately 50 per cent of UV radiation at 360 nm sensitivity to UVA radiation has also been demonstrated in (UVA). As addressed earlier, the penalty for providing this aphakic eyes.
final barrier of UV radiation protection for the retina isincreasing yellowing and other changes that eventually result 3.5.15 The retina is uniquely configured to respond to in opacification and cataract formation (cataractogenesis).
the narrow band of solar radiation that typically reaches thesurface of the planet, namely the visible spectrum. As 3.5.11 The UV radiation absorption capability of the mentioned previously, that spectrum generally extends anterior segment of the eye results in virtually no UV from 400–700 nm, but the retina is particularly more radiation shorter than 300 nm being passed into the vitreous sensitive to certain wavelengths within that range. That body and only about one to two per cent of UVB and UVA sensitivity peaks at approximately 555 nm (yellow-green) passing through the lens. A unique window of UV radiation due to cone sensitivity under photopic conditions (daylight) transmission has been identified in the lens through which but shifts down towards shorter wavelengths, reaching a disproportionate amount of UV radiation at 320 nm approximately 510 nm (blue-green) at twilight, which (UVA) is transmitted. This is of some interest but does not coincides with the peak rod sensitivity under scotopic represent a significant vulnerability. Since the lens is an conditions (night). This shift between cone sensitivity and avascular and encapsulated structure, its ability to dissipate rod sensitivity is known as the Purkinje Shift.

Chapter 3. Laser beam bioeffects and their hazards to flight operations Top view of left eye 1. epithelium2. Bowman's layer3. stroma4. endothelium and Descemet's membrane 5. anterior chamber (contains the aqueous humour) macula lutea with fovea centralis 5º posterior chamber anterior chamber Internal limiting membrane Nerve fiber layer Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer Retinal pigment epithelium Layers of the retina Figure 3-2. The anatomy of the eye
Manual on laser emitters and flight safety 3.5.16 In some cases, a physiological retinal reaction may be expected. It therefore defines the so-called to UV and IR radiation can be documented. While IR "safe range" from any given laser emission. That radiation is generally invisible, it has been possible to "safe range" relates to actual biological damage and demonstrate spectral sensitivity in the human eye as high as not necessarily to disruptions in visual performance. 1 064 nm (Sliney, et al., 1976).1 c) Minimal ophthalmoscopically visible lesion
3.5.17 To initiate the visual process, the retina must (MOVL). The MOVL can be defined as the
absorb visible radiation. The retina is also capable of minimal lesion caused by a laser beam exposure, absorbing IR radiation. This absorbable radiation (visible which can be seen by direct ophthalmoscopy.
and IR) defines the in-band range and classifies those
Tissue damage may not be immediately apparent lasers that emit photons within this band as having in-band
and it may take over 24 hours for a lesion to laser threat wavelengths.
become visible. In general, the energy required toproduce an MOVL increases as a function of 3.5.18 As mentioned previously, the potential for any distance from the fovea on the retina. Radiant given laser beam to induce bioeffects is not only a function exposure and irradiance thresholds capable of of the physical characteristics of the laser beam itself, but creating MOVLs have been determined for most also of assorted environmental or atmospheric conditions common laser beam wavelengths.
present at the time. To these variables, certain biologicalcharacteristics of the eye must be added that also modifydamage thresholds in the eye. These include: 3.7 LASER BEAM BIOEFFECTS
3.7.1 The range of potential bioeffects associated with photosensitivity level laser beam illumination is a continuum of reversible and tissue vascular supply irreversible histological damages dependent on the physical clarity of the ocular media (transmission and laser beam characteristics, environmental factors and vulnerability of the tissue.
level of light adaptation type of tissue exposed 3.7.2 It is therefore possible to define a broad range and continuum of potential bioeffects, involving the opticalradiation range, that include both pathological damages(either reversible or irreversible) and performance impacts, 3.6 OCULAR LASER BEAM
all of which represent a threat to safe air operations (Figure 3-3). This ranges from distraction, glare and dazzlethrough flash-blindness, assorted after-images and residual There are a few specific terms relevant when addressing scotomas, to retinal burns, retinal hemorrhages and even an laser-beam damage in an eye. These are: ocular hole. It also includes physical and psychologicalphenomena that may further disrupt visual and cognitive a) Maximum permissible exposure (MPE). The MPE
function during a particular task. Consequently, it is not is that level of laser beam energy below which necessary for the MPE to be exceeded or the NOHD to be exposure to a laser beam is not expected to produce violated before a potentially significant effect will occur. adverse biological damage. There are differences inMPE calculations depending on whether the laserbeam is pulsed or continuous. MPEs for the skin andeye for any laser beam and exposure condition areavailable in the American National Standards 1. Sliney, D.H., R.T. Wangemann, J.K. Franks and M.L.
Institute ANSI Z136-1-2000,2 the International Wolbarsht. "Visual Sensitivity of the Eye to Infrared LaserRadiation". Journal of the Optical Society of America, Electrotechnical Commission (IEC) 60825-1: 19983 66(4): pp. 339–341.
and other related international documents.
2. American National Standards Institute ANSI Z136.1-2000.
b) Nominal ocular hazard distance (NOHD). The
"American National Standard for the Safe Use of Lasers".
NOHD is the distance from a laser beam beyond 3. International Electrotechnical Commission IEC 60825-1: which the MPE is not exceeded. Within the NOHD, 1998. "Safety of Laser Products, Part 1; Equipment the MPE may be exceeded and biological damage Classification, Requirements, and User's Guide".
Chapter 3. Laser beam bioeffects and their hazards to flight operations 3.7.3 At the very minimum, any visible laser beam can and are invariably present in and around any discrete laser be potentially distracting and psychologically disruptive.
beam induced focal lesion. This collateral damage is During a critical phase of flight, even a low-powered laser primarily due to other tissue damage mechanisms, such as beam could prove lethal to crew and passengers while not distal effects from occlusion of proximal blood supply or having the power to cause any biological tissue damage.
oedema that disrupts adjacent cell structures and com-presses local blood vessels.
3.7.4 A single exposure to a laser beam may induce several effects at the same time. Such an exposure can be 3.7.6 Generally, the susceptibility of the human eye to distracting (on occasion even terrifying), induce glare or actual damage is also a function of the environmental dazzle effects, cause flash-blindness and create after-images luminance and level of light adaptation at the time of and scotomas, as well as being capable of creating a retinal exposure. For example, any given laser beam would have burn or hole or inducing an intraocular haemorrhage.
to be significantly more powerful to induce similarphotopic (daylight) bioeffects, such as flash-blindness, 3.7.5 A laser beam capable of inducing a retinal burn glare, dazzle and distraction, than such an illumination will also induce a surrounding area of oedema and other under mesopic (twilight) or scotopic (night) conditions. For related biological tissue damage or bioeffects that will the same average power, a pulsed laser beam will have a encompass a much broader area beyond the confines of the higher peak power and is therefore more hazardous than a actual visible lesion itself. The MOVL refers to the smallest CW laser beam. However, when it comes to many of the laser beam induced lesion that is ophthalmoscopically potential bioeffects common to all laser beams, the clinical visible and refers only to lesions visible with direct view and subjective difference between pulsed and CW beams is examination devices and does not extend to microscopic examination techniques. Specialized equipment is neededto see areas of microscopic damage induced by laser beam 3.7.7 Due to their light-collecting capability, viewing exposure. However, it can be anticipated that these changes aids, such as periscopes, telescopes and binoculars, have a are an ever-present part of the tissue bioeffect continuum potential to increase the amount of laser radiation entering vaporization haemorrhage •Ocular holes burn PSYCHOLOGICAL EFFECTS Figure 3-3. Ranges of laser beam bioeffects
Manual on laser emitters and flight safety the eye, thus increasing the hazard. This would increase the MPE, then even a brief direct visualization of the laser NOHD and OD requirements for eye protection. When the beam before a compensatory blink occurs could result in beam diameter is made 50 per cent smaller, the power irreversible biological damage, as well as acute disturb- density of the beam is quadrupled.
ances in visual performance.
3.7.8 Imaging devices that do not provide direct 3.8.3 Due to the strobe effect of some pulsed laser viewing of a laser beam, such as night vision goggles beams, they can be more distracting than CW laser beams (NVG) or forward looking infrared (FLIR) sensors, do not of the same average power. transmit the incoming laser photons directly to the humaneye. These devices use visible photons that have been 3.8.4 If the light proves to only be a trivial distraction, newly generated and then multiplied using photosensitive attention can be rapidly refocused to the aeronautical task materials. The output of these devices is not a laser beam.
at hand with little more than perhaps an inconsequential The new photons emitted out of the viewing port of such time penalty. However, if the light is bright enough, devices are considerably different from those that actually residual psychological and visual bioeffects can prevent enter the light-gathering device. Consequently, although resumption of normal visual and cognitive function and such sensors and their data can be disturbed or destroyed by related performance tasks.
a laser beam, they do provide a significant level of laserbeam eye protection along their line of sight.
3.8.5 When a suspected laser beam exposure occurs, experience has shown that there will be an immediatepsychological reaction as a direct consequence of what mayinitially be perceived as a serious eye injury, especially if 3.8 LASER BEAM BIOEFFECTS
the light is strong enough to induce persistent visual effects.
The resulting mindset will persist until some functionalvision returns but will not completely dissipate until it 3.8.1 This section will elaborate on the individual resolves completely or assurances are given that no features of the bioeffects continuum as they relate to the permanent damage has occurred. Therefore, there may be a eye and air operations. These bioeffects include: period of time during which the exposed aircrew membersmay be functionally disabled, visually and/or psycho- logically. Reactions to such events are an unpredictable glare (also referred to as dazzle) aspect of human nature, but experience has taught us that significant exposures to laser beams under these conditions can result in serious psychological disruptions, inciting panic and necessitating transfer of control of the aircraft to the other flight crew members. retinal haemorrhages Glare and dazzle
3.8.6 Glare and dazzle are two terms often used interchangeably that refer to temporary disruptions invisual acquisition without biological damage. Glare can be 3.8.2 When a person sees a bright light, particularly at caused by virtually any light and is particularly disruptive night, the natural reaction is to look at it. While in flight, under scotopic viewing conditions, especially when the aircrews are particularly sensitive to unexpected bright eyes are fully dark-adapted. However, any glare source in lights. Such a light may be perceived as representing a the cockpit is undesirable. Glare is regarded to be a source- potential threat, such as the prospect of a collision with fixed effect, meaning that as the position of gaze shifts another aircraft or a ground obstacle. Pilots, because of away from the light source, glare effects are diminished.
their extensive training in combination with normal Glare only occurs when the light source is on. The length biological reflexes, instinctively divert their attention of time during which glare is in effect is not only a function toward any new unexpected light in order to assess its of how long the light is viewed but also of the overall dark- significance. A distraction that occurs during a critical adaptation state and pupil size in the target eye. Glare can phase of flight could have serious consequences unrelated be divided into discomfort glare and disability glare.
to the light source's ability to induce actual ocular damage.
Discomfort glare refers to glare of high enough il- If the light is a laser beam illumination that exceeds the lumination that forces the viewer to turn away. Discomfort Chapter 3. Laser beam bioeffects and their hazards to flight operations glare tends to be exacerbated when the overall ambient recover functionally from the flash-blindness. If the visual illumination is low. Disability glare refers to the inability to task being undertaken at the time of exposure is well see an object because of the light. Veiling glare represents illuminated, recovery times will be shorter than recovery the ability of glare to impede visualization of structures from poorly illuminated visual tasks. These recovery times around the glare source beyond the actual size of the glare reflect differences between the photochemical rejuvenation source itself and is a more functional representation of the rate of rods and that of cones.
true level of visual performance degradation.
3.8.11 Flash-blindness can last from several seconds to several minutes and has been shown to be more 3.8.7 Disability glare from an external light can be prolonged in older individuals, largely based on the speed reduced by any intervening interfaces, such as windscreens, and efficiency of recovery mechanisms and richness of canopies or other optical media that scatter incident light.
vascular supply available in the target ocular tissue. CW Scratched or dirty spectacles, contact lenses, as well as the and pulsed laser beams are equally adept at inducing flash- cornea and crystalline lens, may also attenuate the disability glare. However, the more scatter that occurs, thegreater the degrading effect from veiling glare. 3.8.8 Some interface materials can also reradiate at different wavelengths; thus an invisible laser beam can 3.8.12 After-images refer to perceptions, or so-called cause reradiation at a visible wavelength. This effect is not after-effects, which persist following illumination with a likely to be significant outside the NOHD for the invisible bright light. They are often described as light, dark or coloured spots following exposure. Such after-images areessentially a type of flash-blindness, although after-image 3.8.9 It has been shown that glare sensitivity increases effects may last for more prolonged periods of time, often with age as it is a function of age-related changes in the well beyond recovery of the ability to perform visual tasks optical media, particularly the crystalline lens. In general, a required while in the cockpit. After-image effects may visible laser beam is a very bright light that can be an include colour distortion that represents selective cone extremely effective cause of disability glare. Laser beam pigment depletion similar to those induced with flash- induced glare can be initiated by both CW and pulsed laser blindness. However, after-images may persist for much beams, although it tends to be more of a concern with a longer periods than flash-blindness and can persist from CW laser beam source. It also appears that within the visual minutes to hours or several days. They can also have spectrum, all wavelengths have approximately the same different effects depending on the characteristic of the scattering characteristics. Consequently, all colours have background under observation. Like flash-blindness, after- the capacity to induce glare.
images also tend to last longer in older individuals. Theirintensity, density and duration are in direct proportion tothe intensity of the instigating light. 3.8.13 After-images can occur following illumination with both visible and invisible radiation. The latter reflects 3.8.10 Flash-blindness is a visual interference effect normal retinal sensitivity to some of these wavelengths, i.e.
caused by a bright light that persists after the light is to some limited UV or IR bands, or is an expression of terminated. Flash-blindness persists while an eye attempts to actual biological damage.
recover from an exposure to the bright light. The ability ofany given light source to induce flash-blindness is directlyrelated to the brightness of the light and the level of dark adaptation in the target eye at the time of the exposure. Itcan be shown that the brighter the environmental luminance 3.8.14 A scotoma is an after-effect which is either levels to which an eye is adapted at the time of the exposure, temporary (reversible) or permanent. A scotoma in its most the brighter the light needed to induce flash-blindness. The benign form represents a resolving residual after-image.
corollary to this is that the brighter the light in any given However, it can also be permanent and may thus reflect the situation, the longer the ensuing flash-blindness period. This earliest sign of permanent biological tissue damage.
relates directly to the ability of the eye to recover from Scotomas typically follow flash-blindness reflecting normal bleaching of the photosensitive pigments caused by the new biochemical recovery of photosensitive pigments in both bright extrinsic light. During the period of recovery, the rods and cones. The typical scotoma can be caused by luminance conditions of the objects being viewed as a exposure to a bright light but can also be caused by some primary task will also determine how long it takes to non-visible wavelengths. Manual on laser emitters and flight safety 3.8.15 A permanent scotoma can be either relative or absolute. A relative scotoma is an area of the visual field inwhich objects of a certain size, brightness or colour may be 3.8.21 A retinal burn represents more significant and seen while other objects that are smaller, less bright or of a permanent damage induced by intense radiation and is very different colour are not seen. This indicates damage to the characteristic of laser beam induced phototoxic damage. A retina but not complete loss of function. It is a reflection of laser beam focused on the retina is more likely to cause the degree of tissue damage in the immediate area or to its injury than a non-focused beam. The ability of a laser beam vascular supply at a more distant location.
to induce such damage is used as a surgical tool to treatcertain ophthalmological disorders, such as retinal tears and 3.8.16 An absolute scotoma, on the other hand, is a diabetic retinopathy. In the latter case, approximately 1 500 more pronounced manifestation of visual damage and deliberate retinal burns are created with an argon laser essentially represents an area of the visual field where no beam to reduce the risks of retinal neovascularization that object, regardless of size, colour or luminance, is visible. In occurs in about five percent of diabetes mellitus cases.
effect, it represents a part of the retina where there is no However, such laser beam induced events in normal eyes longer any functioning neural retina remaining as a result are otherwise significant, unwanted occurrences. It is also of direct localized tissue damage or disruption of vascular possible that other histological damage, occurring at levels supply or neural pathways elsewhere.
not observable ophthalmoscopically, can account for sur-prising amounts of visual damage without an apparent 3.8.17 The visual performance ramifications of such retinal burn. As mentioned previously, the size of any area scotomas are related to their size and location. Even the of retinal damage will generally extend beyond the confines smallest of absolute scotomas can have devastating visual of the visible lesion because of the other tissue-damage consequences if it occurs directly in the fovea (central mechanisms. A small retinal burn that closes or interrupts vision), as opposed to a few degrees away.
vascular supply or neural pathways can affect a much largerarea of retina, although collateral blood flow may temper 3.8.18 Retinal cones mediate fine visual acuity and this effect to some degree.
are maximally concentrated in and around the fovea,achieving their densest population in a specialized area 3.8.22 It is the ability of a laser beam to induce a called the foveola. Here the visual acuity is maximal as retinal burn that is one of the most ominous unwanted illustrated in Figures 3-4 and 3-5. This highest level in effects in a normal eye, and any resultant visual conse- cone-mediated visual acuity at that location is known as quences will be a direct function of the size and location of central vision. Cone population density, however, quickly
drops off as a function of distance from the fovea,especially outside a 10-degree radius from the fovea. 3.8.23 Direct viewing of a high-powered laser beam on the visual axis will cause burns that have greater visual 3.8.19 This cone distribution accounts for the fact that ramifications than off-axis burns. The retina can sustain 6/6 or better visual acuity occurs within the central one many small burns in the periphery without any obvious degree of the fovea, in the foveola. By five degrees away, physiological consequence. These peripheral lesions, while visual efficiency has dropped off to approximately 6/12 to not usually symptomatic, indicate the presence of a 6/18 and by 10 degrees away, visual degradation reaches significant laser beam exposure in the given operational 6/18 to 6/24. Vision outside the fovea is referred to as environment. In addition, a laser beam has the ability to peripheral vision, which typically degrades to 6/60 to
remain quite powerful even after reflection from shiny 6/120 levels as cones become less common and more surfaces, so that those whose visual attention are directed widely spaced.
away from the primary laser beam may still receive an on-axis reflection from an unexpected quadrant of gaze. In 3.8.20 Therefore, it is the precise location of any some cases, certain reflective sources, such as concave permanent ocular damage relative to the fovea that will mirrors, may concentrate the laser beam even further. Other determine the resulting level of functional visual acuity.
observations related to the ability of a laser beam to induce Any focal lesion in the eye will produce a scotoma.
a retinal burn reveals that the energy requirements to induce Permanent scotomas are usually associated with observable such a lesion generally increase as the distance from the retinal lesions, but the area of scotoma may be much larger fovea increases. Similarly, it has been shown that repetitive than the size of the retinal lesion suggests because of re-exposures (multiple subthreshold exposures) in any collateral histological damage in surrounding tissue.
given area may reduce the threshold for inducing biological Consequently, the size and location of the retinal lesion will damage at that location. This further supports the need to determine the overall visual effect of any given lesion in an redirect gaze immediately away from any laser beam that enters the eye.
Chapter 3. Laser beam bioeffects and their hazards to flight operations Degrees away from foveola Figure 3-4. Visual acuity as a function of cone distribution
(area centralis): Optic disc (physiological blind spot): 1.5 mm (5°) × 1.75 mm (7°) Parafovea: ≥3 mm (10°) Outside posterior pole (peripheral retina): Figure 3-5. Visual acuity as a function of retinal location
Manual on laser emitters and flight safety eye, the sclera-globe rupture. Such laser beams would needto be very powerful to retain that capability at considerable 3.8.24 A retinal haemorrhage will occur if a laser distances and would not likely be associated with laser beam disrupts a blood vessel somewhere in the eye. The beams routinely encountered in civil aviation. Furthermore, characteristics of that haemorrhage will depend on the lasers of this peak power at extended ranges are likely to location of the damaged blood vessel within the retina, its have other much more significant effects that would distribution and the orientation of the cell structure at the overshadow the eye and vision considerations. disruption site. Haemorrhages involving superficial retinalvessels will tend to follow the nerve fibre layer and assumea flame-shaped configuration as the blood follows the nerve fibres out radially from the optic nerve. Haemorrhages inretinal layers deeper than the nerve fibre layer tend to be 3.8.27 In addition to the previous discussion of the dot- or blot-shaped. This blood can originate from deeper psychological and ocular effects associated with laser beam vascular supplies, such as from the choroid (middle layer) exposures, there are other bioeffects that need to be of the eye. It is also possible to disrupt a vessel or vascular addressed. It is quite common in response to a perceived plexus to the extent that a large intraocular bleed occurs.
bright light, particularly if it induces symptoms or a lesion, This blood may either collect on the retinal surface as a for those affected to rub their eyes. This can induce preretinal haemorrhage or diffuse into the vitreous cavity.
mechanical trauma to the cornea and conjunctiva that is Blood that enters the vitreous body will tend to remain unrelated to the biological damage mechanisms of laser localized, particularly in younger individuals, but with beams. For example, excessive rubbing can induce con- increasing age, the jelly-like vitreous body liquefies and junctival haemorrhages and superficial epithelial lesions of will allow blood to diffuse throughout the entire vitreous the cornea or even corneal abrasions that can induce further cavity. This change in the vitreous body with age is a symptoms and discomfort that are unrelated to, but often normal aging process known as vitreal liquefaction, but it attributed to, the laser beam itself. This can become even may also occur as a result of other pathological processes more problematic if the rubbing occurs over contact lenses, such as trauma.
especially lenses made from rigid materials.
3.8.25 A haemorrhagic event can have significant 3.8.28 As a result, best corrected visual acuities and visual impact. Recovery will depend on the location of the any ocular damage must be carefully recorded in the bleed and other induced cytoarchitectural disruptions, as medical record so that a determination can be made, either well as the rate of reabsorption of the blood, e.g. from the by on-scene medical examiners or by subject matter experts vitreous body, where it acts as a light-blocking filter. In who later review such cases as to cause and effect. A general, blood in the vitreous cavity will take approximately corneal and retinal drawing should always be made to show six to twelve months to resolve spontaneously but will not the precise location and configuration of any lesions related always do so. In many cases, removal of the cloudy vitreal to the event. This is extremely important especially since contents will be required surgically (vitrectomy) to restore a these events invariably become medical, occupational, legal clear ocular medium within the vitreous cavity. In some and political controversies at some point.
cases, blood in the vitreous body will fibrose into localizedareas of vitreal opacification or induce fibrous strands that 3.8.29 Beyond the description of biological damage can produce retinal traction or retinal tears.
mechanisms and related bioeffects associated with laserbeams, consideration should be given to the visualperformance ramifications of this damage from a different perspective. Those categories of visual performance thatare related to either temporary or permanent laser beam 3.8.26 It is possible with a laser beam to disrupt tissue effects include: central visual acuity, peripheral visual to such an extent that neither a burn nor a haemorrhage acuity, colour perception, contrast sensitivity and occurs, but rather a tear in the tissue is caused. This can be stereopsis. Therefore, the consequences of specific laser a deleterious effect from exposure to high-peak power laser beam induced lesions must also be viewed with regard to beams of certain wavelengths. But this can also be used their ability to affect these other areas of visual therapeutically to disrupt unwanted membranes or traction performance. In many cases, these visual functions will be bands within the eye. Such tissue disruption may be tested to determine deviations from normal and to monitor complete, either extending through an entire tissue layer, recovery. It should be noted that colour perception such as the retina and choroid, or with more powerful laser screening (which should include both red/green and beams, to create a tear or hole in the entire outer coat of the yellow/blue testing) can be particularly useful in Chapter 3. Laser beam bioeffects and their hazards to flight operations identifying phototoxic retinal damage and may indicate 3.10 MEDICAL EVALUATION OF
laser beam damage even when the Amsler grid and Snellen LASER BEAM INCIDENTS
visual acuity tests are normal. This ability to identifyphototoxic events with colour vision tests has been shown 3.10.1 The medical tools and methodologies to exceed the ability of the Amsler grid to identify the recommended for evaluating suspected laser beam induced presence of an actual laser beam related injury. Therefore, injuries are described in Chapter 7. It is extremely colour vision testing (including red/green and blue/yellow important that every effort be made to promptly record all testing) remains a significant tool to assess the level and relevant details of the exposure at the earliest opportunity degree of potential damage related to any light or laser as this may have critical occupational, medical, legal and beam exposure.
operational value to all parties concerned. Experienceshows that in many such exposures, damage attributed to 3.8.30 Individual variations in affected eyes make laser beam illuminations has, in fact, another cause. The accurate prediction of rate and degree of recovery almost following report gives an example of this.
impossible. The closer the lesion to the macula, the greaterthe likelihood of significant visual impairment, but On 29 November 1996, at about 6:50 p.m. local appearance alone is not always a good indicator of time, the captain of an Embraer 120 sustained an function. Some eyes with significant lesions seen with the eye injury when hit by a laser beam during ophthalmoscope have surprisingly good visual function.
approach to Los Angeles, California (United Other eyes may have significantly reduced visual function States). The aircraft was at 6 000 feet MSL in VMC with very little to see ophthalmoscopically. The normal on right base for a visual approach to runway 24R.
retina is transparent and it is only with some of the newer The captain was looking for other traffic through instruments, such as the confocal scanning ophthalmoscope the right window of the cockpit when he was struck that subtle retinal changes can be studied. The most subtle in his right eye by a bright blue beam of light. As lesions may be impossible to detect except with electron the flight continued, it became more difficult for the microscopy. Corneal lesions are somewhat easier to captain to see with his right eye because of evaluate clinically. As with the retina, location is critical. A increasing pain and tearing. By the time the aircraft small corneal scar in the visual axis will affect vision was established on final approach, the captain was severely, while a dense peripheral corneal scar may have no in so much discomfort that he relinquished the effect on visual acuity. control to the co-pilot who completed the landing.
The captain requested immediate medical attention,and examination at a local hospital revealedmultiple flash burns to his right cornea. The captain 3.9 THE FUTURE
was also examined by specialists at ArmstrongLaboratory, Brooks AFB, San Antonio, Texas. This 3.9.1 Although much is known about laser beam examination revealed no evidence of permanent bioeffects, the proliferation of laser technology mandates effects from the exposure. Investigators from the continued research as new laser beam wavelengths and FDA attempted without success to identify the laser characteristics are developed. Several areas of concern source of the laser beam. There were no NOTAMs related to laser beam exposure remain to be defined, such in effect for laser light activity in the Los Angeles as cumulative effects as a result of repetitive low-intensity area at the time of the incident.
exposures and age-related sensitivities. 3.9.2 Another area of interest is neuroprotective (Summary of NTSB Full Narrative Report drugs. While no effective neuroprotective agents have yet been identified, several types are being pursued in thehopes of eliminating or decreasing retinal sensitivity to 3.10.2 In this report, the initial diagnosis of corneal injury from laser beam exposure.
damage ("multiple flash burns to his right cornea") cannotbe directly attributed to a visible laser beam because light 3.9.3 On the other hand, the increasing use of a variety passes through the cornea without affecting it. The damage of medications can potentially photosensitize the skin and to the cornea was most likely caused by rubbing of the eye the eyes, increasing their susceptibility to phototoxic in response to the light beam exposure.
damage. Research in this area remains difficult. It isexpensive, complicated, time consuming and would need to 3.10.3 The inability of some examiners to correctly encompass a huge and ever-expanding pharmacopoeia of diagnose an injury following laser beam exposure can be both natural and synthetic drugs.
attributed to a lack of understanding of the significance of Manual on laser emitters and flight safety the events involved and inadequate experience with this Green, R.P., R.M. Cartledge, F.E. Cheney and kind of injury. It is common for people to vigorously rub A.R. Menendez. "Medical Management of Combat Laser their eyes in response to an insult they may have received, Eye Injuries". USAFSAM-TR-88-21, October 1988.
whether it was from radiation or particulate matter. They [Requests can be addressed to: Freedom of Information Act often do so instinctively, sometimes in a state of panic and Office (FOIA), 311th CS/SCSD, 8101 Arnold Drive, in such a coarse way that they induce ocular damage to the Brooks AFB, TX 78235-5367, United States.] conjunctiva and cornea. This damage can be misconstruedas caused by the laser beam itself when, in fact, it was a International Electrotechnical Commission IEC 60825-8: self-induced mechanical trauma after the event. It is 1999. "Safety of Laser Products, Part 8; Guidelines for the therefore absolutely critical, when such events occur, that Safe Use of Medical Laser Equipment".
these patients be examined by subject-matter experts withadequate experience and knowledge of laser beam injury Ivan, D.J. and H.J. O'Neill. "Laser Induced Acute Visual patterns and source characteristics. Only such experts can and Cognitive Incapacitation of Aircrew, Protection definitively establish whether or not such events are related Management, and Cockpit Integration". AGARDOGRAPH to a laser beam exposure. AGARD-AR-354, Chapter 11: pp. 73–85, April 1998.
[Requests can be addressed to: NATO Research and 3.10.4 Physical characteristics and other historical Technology Organization, BP-25, 7 Rue Ancelle, F-92201, details related to the laser beam and exposure setting need Neuilly-Sur-Seine, CEDEX, France.] to be evaluated carefully. For the most part, this will bebeyond the capability of ordinary medical practioners who Lerman, S. Radiant Energy and the Eye. Macmillan lack a comprehensive background in lasers and their Publishing Co., Inc. New York, 1980.
bioeffects. In the absence of national laser injurymanagement centres, an international point of contact Sliney, D.H. and M.L. Wolbarsht. Safety with Lasers and should be established to help facilitate the recording of Other Optical Sources — A Comprehensive Handbook.
Plenum Press, New York, 1982.
Thomas, S.R. "Review of Personnel Susceptibility toLasers: Simulation in Simnet-D for CTAS-2.0". AL/OE- TR-1994-0060, January 1994.
[Requests can be addressed to: Freedom of Information Act American National Standards Institute ANSI Z136.3-1996.
Office (FOIA), 311th CS/SCSD, 8101 Arnold Drive, "Laser Safety and the Healthcare Environment".
Brooks AFB, TX 78235-5367, United States.] Boettner, E.A. and J.R. Wolter. "Transmission of the Zuclich, J.A. and J. Taboada. "Ocular Hazard from UV Ocular Media". Investigative Ophthalmology and Visual Laser Exhibiting Self-Mode-Blocking". Applied Optics 17, Science 1, pp. 776–783.
pp. 1 482–1 484.
Chapter 4
completely blinded in the right eye. After-imageeffects also impaired vision in his left eye. He 4.1.1 An increasing incidence of in-flight laser beam reported that his inability to see lasted 30 seconds illuminations of flight crew personnel has been reported in and for an additional period of two minutes he was recent years. Incidents have occurred primarily near unable to interpret any instrument indications. The airports located in close proximity to large cities, resort captain assumed control of the aircraft and destinations and entertainment venues. Such illuminations continued the climb.
have resulted in aversion responses (blinking, squinting,head movement), temporary visual impairment (TVI), (Summary of NTSB Aviation Accident/Incident temporary vision loss (TVL), a variety of psychological Database Report LAX96IA032) effects and evasive actions.
4.1.3 These incidents made it clear that TVI at On 19 November 1993, at 10 p.m. local time, a illumination levels much lower than those normally B-737 departing Las Vegas, Nevada (United States) associated with physical eye injury could affect flight was struck by a green laser beam at 500 feet AGL.
safety. On 11 December 1995, a moratorium on all outdoor The beam entered the cockpit through the co-pilot's laser activities in Las Vegas was declared. window, flash-blinding both pilots for 5-10 seconds.
The co-pilot reported problems with his right eye 4.1.4 There are two situations where outdoor laser and needed medical attention at the end of the operations may compromise aviation safety. The first is flight. The captain of the flight stated as his opinion where the MPE is exceeded and physical injury to the eye that if the laser beam had passed through the front can occur. The second is the situation where the MPE is not windshield illuminating both pilots at a more direct exceeded, but where there is a potential for functional angle, they would have lost control of the aircraft.
impairment, such as flash-blindness, after-image and glare The laser beam source was reported to have been that can interfere with the visual tasks of the pilots during located at one of the hotels near the airport.
critical phases of flight. The two excerpts above arebelieved to be examples of the second situation.
(Summary of Report of Irregularity, dated 24 November 1993) 4.1.5 There are obvious flight safety risks associated with laser beam illumination during critical phases of flight 4.1.2 During the following two years in the vicinity of (especially procedures requiring steady-state turns). These Las Vegas airport, there were more than 150 laser beam are caused by ocular, vestibular and psychological effects, illuminations of air carriers, regional carriers, military which individually or combined may lead to loss of aircraft and local helicopter operators, including emergency situational awareness (LSA). TVI leaves the pilot reliant and law enforcement operators.
upon other sensory input, which may provide inadequate butcompelling information, resulting in incorrect decisions.
On 30 October 1995, at 6:10 p.m. local time, a TVI can lead to startle, distraction, disruption, disorientation B-737 was climbing through 4 500 feet AGL on and in extreme cases, complete incapacitation.
departure from Las Vegas when the first officer,who was the flying pilot, was hit by a laser beam.
4.1.6 Pilots receive most of their flight information He immediately experienced eye pain and was visually, and in order to maintain situational awareness in a Manual on laser emitters and flight safety dynamic environment, they rely on frequent reference to a) Sight (vision). This is the single most important
their instruments. This reliance is greater at night and sense for maintaining spatial orientation during becomes total in instrument meteorological conditions flight. When vision is impaired, spatial orientation is degraded because motion and position cuesprovided by other senses are not reliable during 4.1.7 It is important to understand how trained pilots interpret, integrate and process information without visualreference to the outside world. Thorough instrument flight Vision can be divided into peripheral and central training is a prerequisite for maintaining normal task per- vision. Peripheral vision provides low resolution formance, information integration and situational aware- but is highly sensitive to movement and light. It is ness when operating under instrument flight rules (IFR).
primarily concerned with the question of "where",thus supporting spatial orientation. Central vision 4.1.8 Pilots use a visual scan technique of glancing at, provides high resolution and colour perception but rather than dwelling upon, the flight instruments. Pilots is less sensitive to light. It is primarily concerned construct mental images of their position in space from with the question of "what". With the loss of visual information provided by the flight instruments. Spatial orientation cues, inadequate but compelling in- orientation is maintained through the brain's comparison of formation from other senses causes a variety of visual inputs with a pre-existing mental model. When illusions, sometimes leading to overwhelming SD.
conditions permit, this model is continually updated withreference to the outside world for comparison and b) Vestibular sense (sense of equilibrium). The
vestibular apparatus provides information from theinner ear about motion and balance. In addition, themiddle ear provides information about ambient 4.2 SITUATIONAL AWARENESS
pressure changes. Normally, visual input willsuppress input from other senses. Because flight 4.2.1 Situational awareness (SA) is the accuracy by motion is different from that of everyday activities, which a person's perception of his environment mirrors the loss of visual input is critical, as vestibular reality. SA is determined by several factors. Anything that information alone may result in illusory perception leads to a loss of SA can create a flight safety hazard. One of flight attitude and motion. For example, to of the most critical factors, and the one most likely to be stimulate the inner ear, an angular acceleration of affected by laser beam illumination, is spatial orientation. 0.5 to 2.2 degrees per second per second isrequired. When the angular acceleration ceases, 4.2.2 Loss of spatial orientation is called spatial such as when a constant rate turn has been disorientation (SD). It can be classified into three types: established, the vestibular apparatus is no longerable to detect the turn. If visual input is absent, Type I (unrecognized SD) occurs when a person is pilots will not recognize that the aircraft continues unaware of being disorientated; Type II (recognized SD) occurs when a person isaware of being disorientated and is able to c) Proprioception (kinaesthetic sense). A variety of
compensate for it; and sensory nerve endings in the skin, the capsules ofjoints, muscles, ligaments and deeper supporting Type III (incapacitating SD) occurs when a person structures are stimulated mechanically and, hence, is aware of being disorientated but is unable to are influenced by the forces acting on the body.
compensate for it.
These proprioceptive mechano-receptors provideuseful equilibrium information based on sensation 4.2.3 A laser beam illumination may cause all three of position and movement. The kinaesthetic sense is types of SD but is most likely to cause Types II and III.
better known to pilots as "seat-of-the-pants". Alone,the kinaesthetic perception of an aircraft's attitudein space is unreliable but can easily be overcome by 4.3 ORIENTATION IN FLIGHT
more vital sensory input. 4.3.1 Orientation in flight is determined primarily by d) Hearing (audition). The auditory system provides
cues provided by the following four senses: information about sound level, pitch and direction.
Chapter 4. Operational factors and training of aircrew Pilots learn to recognize certain sounds during In-flight procedures during and after
flight. For example, airflow over the windscreen laser beam illumination of the cockpit
during acceleration and deceleration of the aircraftand the change in pitch as the engine power-setting 4.4.1 If a pilot is exposed to a bright light suspected changes can be detected.
to be a laser beam, the following steps are recommended toreduce the risk unless the specific action would com- 4.3.2 Loss of visual references caused by a laser beam promise flight safety: illumination, coupled with inadequate information from thevestibular apparatus, the proprioceptive mechano-receptors Look away from the light source.
and the auditory system, may result in SD (often referred toby pilots as "vertigo"), which can lead to accidents.
Shield eyes from the light source.
Disorientation demonstration courses and laser-awarenesstraining are therefore recommended.
Declare visual condition to other pilots.
Transfer control of the aircraft to another pilot.
Switch over to instrument flight.
Engage autopilot.
Notices to airmen (NOTAMs) should be consultedfor location and operating times of laser activities Manoeuvre or position the aircraft such that the and alternate routes should be considered.
laser beam no longer illuminates the flight deck.
Aeronautical charts should be consulted for Assess visual function, e.g. by reading instruments permanent laser activities (theme parks, research or approach charts.
facilities, etc.).
Avoid rubbing eyes.
In-flight procedures prior to entering
airspace with known laser activity
Notify air traffic control (ATC) of a suspected in-flight laser beam illumination and, if necessary, Exterior lights should be turned on to aid ground declare an emergency.
observers in locating and identifying aircraft.
4.4.2 It is important to notify appropriate authorities The autopilot should be engaged.
of a suspected in-flight laser beam illumination. Uponlanding, the pilot should notify the authorities and provide One pilot should stay on instruments to minimize details about the incident, then seek immediate medical the effects of a possible illumination.
evaluation, preferably by a qualified vision specialist.
Documentation of incidents and medical examinations are Flight deck lights should be turned on.
covered in Chapters 6 and 7, respectively.
Chapter 5
"Note 3.— The protected flight zones are established in order to mitigate the risk of operating laser emitters in the 5.1.1 This chapter provides guidance for determining vicinity of aerodromes". and minimizing the potential adverse effects of outdoorlaser operations on aviation safety. Provisions* concerning 5.1.2 Contracting States may be guided by the laser emitters and protected flight zones are contained in: following text examples when controlling the hazards oflaser beam emissions or enacting regulations in accordancewith Annexes 11 and 14: Annex 11 — Air Traffic Services a) No person shall intentionally project, or cause to be "2.17.5 Adequate steps shall be taken to prevent projected, a laser beam or other directed high emission of laser beams from adversely affecting flight intensity light at an aircraft in such a manner as to create a hazard to aviation safety, damage to theaircraft or injury to its crew or passengers.
Annex 14 — Aerodromes, Volume I — Aerodrome Design Note.— Also see Annex 14, Volume I, and Operation b) Any person using or planning to use lasers or other "Laser emissions which may endanger
directed high-intensity lights outdoors in such a the safety of aircraft
manner that the laser beam or other light beam mayenter navigable airspace with sufficient power to " Recommendation.— To protect the safety of
cause an aviation hazard shall provide written aircraft against the hazardous effects of laser emitters, the notification to the competent authority. following protected zones should be established aroundaerodromes: c) No pilot-in-command shall deliberately operate an aircraft into a laser beam or other directed high- — a laser-beam free flight zone (LFFZ) intensity light beam unless flight safety is protected.
a laser-beam critical flight zone (LCFZ) This may require mutual agreement by the operator — a laser-beam sensitive flight zone (LSFZ) of the laser emitter or light source, the pilot-in-command and the competent authority. "Note 1.— Figures 5-10, 5-11 and 5-12 may be used to determine the exposure levels and distances that adequatelyprotect flight operations. 5.2 AIRSPACE RESTRICTIONS
"Note 2.— The restrictions on the use of laser beams in the three protected flight zones, LFFZ, LCFZ and LSFZ, 5.2.1 To protect the safety of aviation in the vicinity refer to visible laser beams only. Laser emitters operated by of aerodromes, heliports and certain other areas, such as the authorities in a manner compatible with flight safety low-level visual flight rules (VFR) corridors, it is necessary are excluded. In all navigable air space, the irradiance to protect the affected airspace against hazardous laser level of any laser beam, visible or invisible, is expected tobe less than or equal to the maximum permissible exposure(MPE) unless such emission has been notified to the * The provisions are not intended to confer any responsibility authority and permission obtained. onto airport operators.
Manual on laser emitters and flight safety beams. For non-visible laser beams, the nominal ocular surface up to and including 3 050 m (10 000 ft) AGL (see hazard distance (NOHD) value is the sole consideration.
Figures 5-1, 5-2 and 5-3). This zone may have to be For visible laser beams, in addition to the NOHD, visual adjusted to meet air traffic requirements. Within this disruption must also be considered.
airspace the irradiance is not to exceed 5 µW/cm2 unlesssome form of mitigation is applied. Although capable of 5.2.2 According to in Annex 14, airspace causing glare effects, this irradiance will not produce a around aerodromes should be designated as laser-beam level of brightness sufficient to cause flash-blindness or sensitive flight zones, laser-beam critical flight zones, and laser-beam free flight zones, in order to prevent visiblelaser beams from interfering with a pilot's vision, even ifthe maximum permissible exposure (MPE) is not exceeded.
The beam from a visible laser must not enter any zone, Laser-beam sensitive flight zone (LSFZ)
when the irradiance is greater than the corresponding visualinterference level, unless adequate protective means are 5.2.5 The LSFZ is the airspace outside the LFFZ and employed to prevent personnel exposure. Lasers with beam LCFZ where the irradiance is not to exceed 100 µW/cm2 irradiances less than the MPE but exceeding the sensitive unless some form of mitigation is applied. The level of level or critical level, may be operated in the sensitive zone brightness thus produced may begin to produce flash- or critical zone, respectively, if adequate means are used to blindness or after-image effects of short duration; however, prevent aircraft from entering the beam path. this limit will provide protection from serious effects. TheLSFZ need not necessarily be contiguous with the otherflight zones.
Laser-beam free flight zone (LFFZ)
Normal flight zone (NFZ)
5.2.3 The LFFZ is the airspace in the immediate proximity to the aerodrome, up to and including 600 m 5.2.6 The NFZ is any navigable airspace not defined (2 000 ft) above ground level (AGL), extending 3 700 m as LFFZ, LCFZ or LSFZ. The NFZ must be protected from (2 NM) in all directions measured from the runway centre laser radiation capable of causing biological damage to the line, plus a 5 600 m (3 NM) extension, 750 m (2 500 ft) on each side of the extended runway centre line of eachuseable runway. Within this zone, the intensity of laserlight is restricted to a level that is unlikely to cause any 5.2.7 Figures 5-1 through 5-3 define the zones visual disruption. The following conditions are applicable established to protect aircraft in navigable airspace. The dimensions indicated are given as guidance but have beenfound to protect safety well.
a) parallel runways are measured from the runway centre line toward the outermost edges, plus the 5.2.8 The amount of airspace affected by a laser airspace between runway centre lines; operation varies with the laser systems output power, whichis measured in watts or joules. The following maximum b) within this airspace, the irradiance is not to exceed irradiance levels (MILs) can be used for evaluating laser 50 nW/cm2 unless some form of mitigation is activities in close proximity to an aerodrome: applied. The level of brightness thus produced isindistinguishable from background ambient light; a) LFFZ: MIL is equal to or less than 50 nW/cm2; b) LCFZ: MIL is equal to or less than 5 µW/cm2; c) to allow laser operations below the arrival path, a 1:40 slope may be applied to the 5 600 m exten-sions. This slope is calculated from the runway c) LSFZ: MIL is equal to or less than 100 µW/cm2; d) NFZ: MIL is equal to or less than the MPE for CW Laser-beam critical flight zone (LCFZ)
or pulsed lasers.
5.2.4 The LCFZ is the airspace within 18 500 m Note.— Items a), b) and c) refer to visible laser (10 NM) of the aerodrome reference point (ARP), from the emissions only. Chapter 5. Airspace safety flight zone
flight zone
To be determined by
free flight
Note.— The dimensions indicated are given as guidance only. Figure 5-1. Protected flight zones
Note.— The dimensions indicated are given as guidance only. Figure 5-2. Multiple runway laser-beam free flight zone (LFFZ)
Manual on laser emitters and flight safety 5.2.9 Protective means (mitigation) are required to c) establish additional LSFZs, if required, to protect protect pilots and other personnel when the visual locations of aviation activity that may also be interference level is exceeded. Redundant systems are affected, such as substantial helicopter traffic advisable in locations noted for heavy air traffic.
operating below 300 m (1 000 ft), VFR corridors,the airspace around high-energy lasers used tosupport astronomical observatories, active training 5.3 AERONAUTICAL ASSESSMENT
5.3.1 The procedures outlined below may be used to d) consider the laser operations in relationship with evaluate the potential effect of laser activity on aircraft the established zones. Use the MILs established by operations. The proponent should notify the competent the competent authority when evaluating laser authority in sufficient time to allow an aeronautical assess- activities in proximity to an aerodrome; ment to be completed.
e) review airspace and aircraft operations that may be 5.3.2 A Contracting State may provide a submission affected by the proposal; form which, when completed, will provide sufficientinformation for an aeronautical assessment to be f) coordinate with local officials, e.g. aerodrome completed. A sample "Notice of Proposal to Conduct managers, air traffic managers, military represen- Outdoor Laser Operations" form and instructions are tatives, local police organizations; attached in Appendix A. The competent authority should: g) convene a local laser working group (LLWG) if the a) determine the location of the laser activity and the operations appear to be complex or controversial; laser MPE and NOHD; h) consider the proponent's proposed mitigation b) plot the LFFZs, LCFZs and LSFZs at aerodromes; measures and any additional measures taken to PROTECTED FLIGHT ZONES Laser-beam sensitive flight zone
Laser-beam critical flight zone
Laser-beam free flight zone
50 nW/cm2
Aerodrome reference point AGL is based on published aerodrome elevation Figure 5-3. Protected flight zones with indication of maximum
irradiance levels for visible laser beams
Chapter 5. Airspace safety ensure that aircraft operators will not be exposed to 2) The laser beam divergence and output power or laser emissions that have the potential to impair pulse energy emitted through the system their performance of duties. Such measures include, aperture may be adjusted to meet appropriate but are not limited to, physical, procedural, manual exposure levels.
and automated control measures; 3) Beams can be directed in a specific area.
i) compile a cumulative impact assessment on per- Directions should be specified by giving manent or long-term laser operations effects on bearing in the azimuth scale 0–360 degrees and local operations; elevation in degrees ranging from 0–90 degrees,where 0 degrees is horizontal and 90 degrees is j) assess the capability of the affected ATC facilities vertical. Both true and magnetic bearings to provide real-time management of air traffic to should be given.
ensure no cockpit illuminations by the laser beams; 4) Manual operation of a shutter or beam- k) coordinate with the proponent, identify objection- termination system can be used in conjunction able effects and negotiate appropriate mitigation to with airspace observers. Observers should be protect aviation safety; and trained and able to see sufficient airspacesurrounding beam paths to terminate the beam l) communicate to the proponent and all participating prior to illumination of aircraft.
authorities the completed aeronautical assessment.
5) Scanning the laser beam may reduce the level If the proposal is complex or controversial, the of illumination; however, it may increase the competent authority should document all pertinent potential risk of illumination.
information and disseminate copies as appropriate.
6) Automated systems designed to detect aircraft and automatically terminate or redirect thebeam or shutter the system may be used. The 5.4 CONTROL MEASURES
proponent should include detailed informationthat describes the operation of the automated Physical, procedural and automated control measures system, its effectiveness and how it can be established to ensure that aircraft operations will not be tested for full functionality prior to each use.
exposed to levels of illumination greater than the respectiveMILs considered acceptable should meet one or more of thedescriptions listed below: a) ATC control measures: 5.5.1 If the proponent's notification satisfies the requirements of the aeronautical assessment, the competentauthority should issue, as a minimum, the following: 2) Voice advisory (e.g. automatic terminal information system (ATIS), pilot-controller a) a statement advising the proponent that his notification satisfies the requirements of thecompetent authority and is approved subject to 3) Airspace restrictions; conditions or limitations (such as aircraft spotterrequirements), as applicable; whereas the proponent must ensure that the operator controlmeasures are in accordance with one or more of the b) a statement to the proponent that changes should not be incorporated into the proposed activity oncepermission has been granted, unless approved by b) Operator control measures: the competent authority in writing; 1) The laser beam may be physically blocked c) a statement that the proponent notify the (terminated beam) to prevent laser light from appropriate authority or their designated represen- being directed into protected volumes of tative of any changes to show start/stop times or cancellation 24 hours in advance; Manual on laser emitters and flight safety d) a statement that approval does not relieve the AIRBORNE TO GROUND LASER ACTIVITY WILL BE sponsor or operator of responsibility for complying CONDUCTED ON (dates), BETWEEN (lat./long., with the mitigation agreed upon, the laws, ordin- altitude) AND BELOW. AVOID AIRBORNE HAZARD ances or regulations of any relevant authority; and BY (NM). THIS LASER BEAM MAY BE INJURIOUSTO PILOTS/AIRCREW AND PASSENGERS EYES.
e) NOTAM. (See examples in 5.5.4.) AIRBORNE LASER ACTIVITY WILL BE 5.5.2 If the proponent's notification does not satisfy CONDUCTED ON/FROM (dates), AT/FROM (times/ the requirements of the aeronautical assessment, the UTC), BETWEEN (NAVAID ID, type, radial) RADIAL competent authority should issue a statement advising the (dist.) NAUTICAL MILES, (lat./long.), AND (NAVAID proponent that an objection is being issued. Specifically, it ID, type, radial) RADIAL (dist.) NAUTICAL MILES, (lat./ should indicate why the proponent does not satisfy safety long.), BETWEEN (altitude) MSL AND (altitude) MSL (or requirements, and that new data or other appropriate the surface). AVOID AIRBORNE HAZARD BY (NM).
information may be submitted for consideration. If THE LASER LIGHT BEAM MAY BE INJURIOUS TO negotiations to resolve any objectionable effects have not PILOTS/AIRCREW AND PASSENGERS.
been successful, the objection should stand. 5.5.3 To enhance aviation safety, a NOTAM should be Sample publication format
prepared alerting pilots of known laser activities. It is of a permanent laser site
important to emphasize the hazardous effects and otherrelated phenomena that may be caused by laser beams.
(place, city, province or state).
5.5.4 The competent authority should provide UNTIL FURTHER NOTICE A LASER LIGHT information for the publication of a NOTAM* as shown in DEMONSTRATION WILL BE CONDUCTED NIGHTLY the following sample formats. Laser activities that last BETWEEN SUNDOWN AND DAWN AT THE (place, more than 180 days should be considered permanent (e.g.
city, province or state) (NAVAID ID, type radial) RADIAL annual ongoing activities). Information pertaining to such AT LAT./LONG. RANDOM BEAMS ILLUMINATING activities should be published in applicable aviation (directions indicated) QUADRANTS. THE BEAM MAY BE INJURIOUS TO EYES IF VIEWED WITHIN (NOHDdist.) VERTICALLY AND (NOHD dist.) LATERALLY OFTHE LIGHT SOURCE. FLASH-BLINDNESS OR Sample publication format
LASER LIGHT DEMONSTRATION WILL BECONDUCTED AT (place, city, province or state), NOTAMs concerning temporary laser activity at
(NAVAID ID, type, radial) RADIAL (dist.) NAUTICAL Harboøre in København FIR (issued by the Civil
MILES, (lat./long.). BEAMS FROM SITE PROJECTING Aviation Administration, Denmark)
(direction) BETWEEN RADIALS (xxx-xxx), ON (dates),BETWEEN (time/UTC). LASER LIGHT BEAMS MAY BE INJURIOUS TO PILOTS/AIRCREW AND PASSENGERS EYES WITHIN (nominal ocular hazard A) EKDK B) 0006091900 C) 0006102200 distance) VERTICALLY AND/OR (nominal ocular hazard D) DAILY 1900-2200 distance) LATERALLY OF THE LIGHT SOURCE.
Chapter 5. Airspace safety OF 0.5NM OF THE LIGHT SOURCE.
D) DAILY 1900-2200E) TEMPO NAV WRNG. AIRBORNE TO GROUND Contracting States may wish to establish an incident- LASER ACTIVITY WILL TAKE PLACE WITHIN A reporting system to provide a means of monitoring 10NM RADIUS OF HARBOOERE PSN 563713N unauthorized use of lasers in airspace. Rapid notification 0081130E. THE LASERBEAM WILL OPERATE FROM of an incident will assist in the investigation and possible 10,000FT MSL DOWNWARD AND MAY CAUSE enforcement action against the offender. Sample incident BLINDNESS IF VIEWED WITHIN A VERTICAL report formats are found in Appendix B.
Chapter 6
persistent symptoms or abnormal clinical findings mayrequire referral to an ophthalmologist for further medical Laser beams with the potential to compromise flight safety evaluation and treatment.
may be visible or invisible. Laser beams may cause damageto the retina, especially at higher levels of exposure. The Note.— Chapter 7, entitled "Medical Examination bright light from visible laser beams can cause glare, after- Following Suspected Laser Beam Illumination", provides images and flash-blindness. Exposure to invisible laser guidance for evaluating aircrew and other aviation per- beams may result in pain, vision loss or skin burns, but they sonnel who may have been injured or incapacitated by a are not normally associated with glare and flash-blindness.
laser beam illumination. Damage to the tissue of the eye's cornea and conjunctivarequires a higher exposure level than that required to causedamage to the retina. This is due, in part, to the eye'snatural focusing mechanism that can increase the energy per unit area delivered to the retina. Besides glare, flash-blindness and after-images, other symptoms of laser beam 6.3.1 Documentation of a suspected laser beam light exposure may include pain, eye fatigue, tearing, eye illumination incident has three important functions. First, it irritation and headache. Laser beam light can and has provides information on the effectiveness of current interfered with safe and efficient performance of flight policies and procedures used to protect the navigable procedures by causing temporary distraction, disorientation airspace against hazardous laser beams. Second, it provides and visual incapacitation.
a protocol for medical assessment. Third, it providesupdates on new devices or sources of hazardous laserbeams that may affect visual performance.
6.3.2 Guidance on how to document suspected laser Whenever an unexpected illumination by an unknown beam illumination incidents is provided in Appendix B.
source occurs, a laser incident should be suspected and The two forms (Suspected Laser Beam Incident Report and reported. It is recommended that all suspected laser beam Suspected Laser Beam Exposure Questionnaire) may be incidents be reported to the national aviation medicine and used for investigation of illumination incidents. The report flight safety authorities. In general, individuals should, should be completed by the illuminated persons as soon as without delay, consult an optometrist, ophthalmologist or possible after the incident. The questionnaire may be used designated medical examiner whenever they have by an official of the competent authority during the initial experienced a suspected laser beam exposure. Those with Chapter 7
Amsler grid for each eye separately (seeAppendix C) 7.1.1 All cases of suspected laser beam exposure Stereopsis (specify test used) should be promptly reported to the medical section of the Colour-vision testing with pseudoisochromatic competent authority. In cases of suspected laser beam plates of each eye separately exposure, two forms should be used: Confrontation visual fields of each eye separately Nondilated funduscopy on each eye separately a) Suspected Laser Beam Incident Report. This form is to be completed by the persons illuminated. 7.2.2 If the results of this examination are normal and the person does not have persistent visual complaints, b) Suspected Laser Beam Exposure Questionnaire.
further examinations are not necessary.
This form may be used by the competent authorityduring the initial interview of an exposed person.
7.2.3 If the results of the basic examination are Note.— Samples of these two forms can be found in abnormal or questionable, an intermediate ocular exam- Appendix B. ination to assess the condition of the person's eyes shouldbe performed. An optometrist or an ophthalmologist may 7.1.2 The following information provides guidance complete the intermediate examination.
for the medical examination and evaluation of those whomay have been exposed to a laser beam.
Intermediate ocular examination
Pupils of each eye separately Slit lamp of each eye separately Automated visual fields of each eye separately 7.2.1 A basic ocular examination should be performed Motility (ductions and versions; cover test) on any person suspected of having been exposed to a laser Dilated funduscopy on each eye separately beam to verify that no permanent damage has occurred andto confirm normal ocular health. An optometrist, ophthal- 7.2.4 If the results of this examination are normal and mologist or a designated medical examiner may complete the person does not have persistent visual complaints, the basic examination. further examinations are not necessary.
Basic ocular examination
7.2.5 If the results of the intermediate ocular examination are abnormal or if visual complaints persist, History (review Suspected Laser Beam Exposure the person should be referred to an ophthalmologist Questionnaire, if available) (preferably a retinal specialist), as advised by the aviation External examination medicine section of the competent authority. This Best corrected visual acuity (near and far) in each ophthalmologist should conduct an advanced ocular Manual on laser emitters and flight safety Advanced ocular examination
Retinal photography Comprehensive testing of colour vision (to includeblue/yellow tests) Electrodiagnostic tests, as needed Scanning laser ophthalmoscopy, as needed Fluorescein angiography, as needed Appendix A
Note.— The sample form below was adapted by ICAO and reproduced with the permission of the Federal Aviation Administration. NOTICE OF PROPOSAL TO CONDUCT OUTDOOR LASER OPERATION(S)
To: (Competent Authority) From: (Applicant) 1. GENERAL INFORMATION
Event or facility Latitude deg (°) min () sec () Longitude deg (°) min () sec () Ground elevation at site Laser elevation above ground Determined by: G GPS G Map G Other (above Mean Sea Level) (if on buildings, etc.) DATE(S) AND TIME(S) OF LASER OPERATION
Testing and alignment
Number of laser configurations [Fill out one copy of page 2 of this notice ("Laser Configuration") for each configuration.]List any additional attachments needed to evaluate this operation (could include maps, diagrams, and details of control measures). 5. DESIGNATED CONTACT PERSON (if further information is needed)
To the best of my knowledge, the information provided in this Notice of Proposal is accurate and correct.
Name (if different from contact person)
Manual on laser emitters and flight safety Fill out one copy of this form for each laser or laser configuration used at the Outdoor Laser Operations site. 1. CONFIGURATION INFORMATION
Name of event/facility This page is configuration number _ of _ Brief description of configuration 2. BEAM CHARACTERISTICS AND CALCULATIONS (check one Mode of Operation only, and fill in only that column)
Mode of Operation G Continuous wave G Repetitively pulsed (not applicable) Maximum power Average power Watts (W)Pulse Energy (not applicable) Joules (J)Pulse Width (not applicable) Seconds (s)Pulse Repetition Frequency (not applicable) (not applicable) Hertz (Hz)Beam Diameter @ 1/e points Centimetres (cm) (not mm)Beam Divergence 1/e @ full angle Nanometres (nm)
W/cm2MPE per pulse J/cm2
VISUAL EFFECT CALCULATIONS (will be used only for visible lasers to calculate SZED, CZED and LFED)
Pre-corrected Power (PCP)
Pulse Energy (J)*4 Maximum Power (from above) Average Power OR Pulse Energy Visual Correction Factor (VCF) Enter "1.0" or use Table 5Visually Corrected Power 3. BEAM DIRECTION(S)
Azimuth (degrees) Magnetic variation (degrees) Minimum elevation angle (degrees, where horizontal = 0°) Maximum elevation angle (degrees) 4. DISTANCES CALCULATED FROM ABOVE DATA
4. (Fill in all three columns for NOHD. If a visible laser, fill in all three columns for SZED, CZED, and LFED.)
Slant range (ft) Horizontal distance (ft) Vertical distance (ft) NOMINAL OCULAR HAZARD DISTANCE
NOHD (based on MPE)
If the laser has no wavelengths in the visible range (400–700 nm), enter "N/A (non-visible laser)" in all blocks below.
For visible lasers, if the calculated visual effect distance is less (shorter distance) than the NOHD, you must enter "Less than NOHD".
SZED (for 100 µW/cm2 level)
CZED (for 5 µW/cm2 level)
LFED (for 50 nW/cm2 level)
G Commercial software (print product name) G Other [describe method (spreadsheet, calculator, etc.)] Appendix A INSTRUCTIONS FOR FILLING OUT NOTICE OF PROPOSAL FORM (page 1)
The information in this form will be used by the Competent Authority to perform an aeronautical study to evaluate the safetyof a proposed laser operation. Provide all information that the Authority may need to perform the study. If additional detailsare necessary, list these in the "Attachments" section of this form.
To: Enter the name, address, phone and fax of the Competent Authority's Office responsible for the area which includes the
laser operation site. (A list of Offices is available at the end of these instructions.)
From: Enter the name, address, phone, fax, and E-mail of the applicant. This is the party primarily responsible for the laser
safety of this operation. In some cases, the applicant is a manufacturer or a governmental agency, and the laser is located at
a different site. In such a case, list the applicant here; the site location is filled in elsewhere in the form.
Report date: This is the date the report is prepared or sent to the Authority. It is not the date of the laser operation.
Event or facility: Enter the event name (for temporary shows) or the facility name (for permanent installations).
Customer: If the laser user is different from the applicant, fill in the "Customer" section; if not, enter "Same as applicant".
Site address: Street address, city, province or state.
Latitude and longitude: Be sure that latitude and longitude are specified in degrees, minutes and seconds. Some maps or
devices may give this information in "Degrees.Decimal" form; this must be converted into degrees, minutes and seconds.
Ground elevation at site: This is the elevation in feet above Mean Sea Level, at the show site. It can be found on a
topographic map or other resource.
Laser elevation above ground: If the laser is on a building or other elevated structure, enter the laser's height in feet above
the ground.
Note.— For lasers on aircraft or spacecraft, attach additional information on the flight locations and altitudes. DATE(S) AND TIME(S) OF LASER OPERATION
Testing and alignment: Enter the date(s) and time(s) during which testing and alignment procedures will take place.
Operation: Enter the date(s) and time(s) during which laser light will enter airspace.
This should be a general overview. Specific laser configurations at the operation are described in detail using the LaserConfiguration form on page 2. If necessary, attach additional pages.
Operator(s): List names and/or titles of operators.
Manual on laser emitters and flight safety On-site phones: There should be at least one working, direct phone link to the operator, or equivalent way of quickly
reaching the operator (e.g. phoning to a central station that reaches the operator via radio). Two telephone numbers are listed
on the form, so one can be used as an alternate or backup.
Describe the control measure(s) used to protect airspace; for example, termination on a building (where the beam path is notaccessible by aircraft including helicopters), use of observers, use of radar and imaging equipment, physical methods oflimiting the beam path, etc. The more that the operation relies on the control measures to ensure safety, the more detailedthe description should be.
Number of laser configurations: List how many "Laser Configurations" you are submitting with this proposal. If a
particular set-up operates with more than one laser, with different beam characteristics (power settings, pulse modes,
divergence, etc.) or has multiple output devices (example: projector heads), then each should be analysed as a separate Laser
Configuration using the form on page 2.
List additional attachments: You may need to add attachments such as maps, diagrams and details of control measures.
Include whatever materials you feel are necessary to assist the Authority in sufficiently evaluating your proposal.
This is the person whom the Authority will contact if additional information is needed. This should be the person with themost knowledge about laser safety at this operation. However, it could also be a central contact person who interfacesbetween the Authority and the laser operation personnel. The Designated Contact Person must work for or represent theapplicant listed in the "From:" area at the top of the form.
The Designated Contact Person should sign the form. However, in some cases the responsibility for the accuracy of theinformation may rest with another person, such as a Laser Safety Officer who is not acting as the contact. Therefore, theperson who has the authority to bind the applicant must sign the form.
A single outdoor operation may have a number of lasers or "laser configurations" — power settings, pulse modes, divergence,etc. On the Notice of Proposal form (page 1), in the first row of the Attachments table, enter the number of different laserconfigurations for the outdoor operation. Then, fill out one Laser Configuration form (page 2) for each different configurationto be analysed.
Alternative analysis: This form and accompanying tables must cover a wide variety of laser configurations. They are
necessarily simplified, and they make conservative assumptions. Some laser configurations may warrant a more complex
analysis. Any such alternative analysis should be based on established methods. Both the methods and the calculations must
be documented
. (See ICAO Doc 9815 for further information.)
Brief description of configuration: Describe the beam projecting or directing system. Include description of site layout.
Attach additional information if more space is required.
This section requires data about the laser beam's characteristics. The data can be obtained from direct measurement,manufacturer specifications or specialized instruments. You can also derive data by making reasonable, conservativeassumptions (for example, that a certain value makes the beam more hazardous than it would be in reality). All data shoulderr on the side of safety. In borderline situations where data accuracy is crucial to compliance, provide additional data onmeasurement techniques, data sources and assumptions. Mode of operation: Determine the mode of operation for this configuration: Single Pulse, Continuous Wave, or Repetitively
Pulsed. Put a check in the appropriate column. Fill out only that column for the remainder of this Beam Characteristics and
Calculations section.
Single Pulse: Lasers that produce a single pulse of energy with a pulse width <0.25 seconds or a pulse repetition
frequency <1 Hz.
Continuous Wave: A laser that produces a continuous (non-pulsed) output for a period >0.25 seconds.
Repetitively Pulsed: Lasers that produce recurring pulses of energy at a frequency of 1 Hz or faster.
Note on "repetitively pulsed" vs. scanning: "Repetitively pulsed" refers to lasers that naturally emit repetitive pulses,
such as Q-switched lasers. The form and tables are not intended for analysing pulses due to scanning the beam over a vieweror aircraft (examples: graphics or beam patterns used in laser displays; scanned patterns used for LIDAR). Pulses resultingfrom scanning are often extremely variable in pulse width and duration. Therefore, for a conservative analysis, assume thebeam is static (non-scanned). Should you rely on scanning to be in compliance, you must 1) provide a more comprehensiveanalysis, documenting your methods and calculations, and 2) document and use scan-failure protection devices. Laser Type: Enter the lasing medium, for example, "Argon", "Nd:YAG", "Copper-vapour", "CO2", etc.
Power: If a continuous wave laser (Column 2), fill in the power in watts. If a repetitively pulsed laser (Column 3), fill in
the average power in watts [energy per pulse (J) × pulse repetition frequency (Hz)]. For both types of power, this is the
maximum power during the operation that enters airspace.
For simplicity and safety you can enter a higher value, the maximum power of the laser; this ignores any additional losses in optical components in the beam path, before the beam enters airspace.
Pulse Energy and Pulse Width: If a single pulse laser (Column 1) or repetitively pulsed laser (Column 3), fill in the pulse
energy in joules and the pulse width in seconds. This is the maximum power that enters airspace. For simplicity and safety
you can enter a higher value, the maximum pulse energy of the laser; this ignores any additional losses in optical components
in the beam path, before the beam enters airspace.
Beam Diameter: Provide the beam diameter using the 1/e peak-irradiance points.
Note.— Diameter is often expressed in millimetres; however, in this form you must enter the diameter in centimetres. Beam Divergence: The beam divergence is the full angle given at the 1/e points. If you know the diameter or divergence
measured at the 1/e2 points instead, multiply by 0.707 to convert to 1/e diameter or divergence.
Note.— Diameter and divergence measurements can be complex. You can use simplifying assumptions for safety. It is safer to assume the beam divergence is smaller than it really is. For example, as a beam travels from the laser through a laser show projector, the divergence generally increases. To be conservative (safer), use the smaller divergence of the beam at the laser, before it goes through the projector. This will assumethe beam is tighter (and thus more hazardous) than it really is.
Manual on laser emitters and flight safety Wavelength(s): Enter the wavelengths of laser light that enter airspace.
If the laser emits multiple wavelengths, each wavelength will need to be analysed separately to find their MPEs and NOHDs. In addition, for lasers emitting visible wavelengths, each wavelength can be analysed separately to find the VisualEffect Distances (SZED, CZED, and LFED corresponding to LSFZ, LCFZ, and LFFZ). This process is described in moredetail in the Visual Effect Distances instructions below.
In all cases of multiple-wavelength lasers, you must document your methods and calculations. If you do not analyse all wavelengths in full, then you must explicitly state your simplifying, conservative assumptions. MAXIMUM PERMISSIBLE EXPOSURE CALCUATIONS
MPE and MPE per pulse: Provide the Maximum Permissible Exposure (MPE) calculation results in the applicable block.
This will be used later to determine the Nominal Ocular Hazard Distance (NOHD).
The easiest way to find the MPE is to use Tables 1 to 4 as described immediately below. These tables provide a simple,conservative method. If you require less conservative levels, use the American National Standards Institute (ANSI) Z136series of standards or other established methods. Both the methods and calculations must be documented. Single Pulse (Column 1): Use Table 1 to find the MPE. Fill in the "MPE per pulse" block in the Single Pulse column.
Continuous Wave (Column 2): Use Table 2 to find the MPE. Fill in the "MPE" block in the Continuous Wave
Repetitively Pulsed (Column 3): Lasers that produce recurring pulses of energy can produce an additional hazard
above that of a single pulse or continuous wave laser. The MPE is adjusted for repetitively pulsed lasers based on its
pulse repetition frequency. The adjusted MPE is designated as MPEPRF. The MPEPRF can be determined using either
the per-pulse energy or the average power. This document provides a simplified method for calculating the MPEPRF for average power with wavelengths in the visible and infrared region. (ANSI Z136 series can provide a lessconservative value in some cases.) Although designated MPEPRF, the values should be placed in either the "MPE" or "MPE per pulse" blocks of the repetitively pulsed column. Following are the simplified methods for determining theMPEPRF for: 1. Ultraviolet wavelengths: Reference the American National Standards Institute ANSI Z136 series.
2. Visible wavelengths: Use Table 3 to determine the MPEPRF. Table 3 results have already applied the correction factor to the CW MPE. Fill in the "MPE" block in the Repetitively Pulsed column.
3. Infrared wavelengths: a) Use Table 2 to find the CW MPE.
b) Use Table 4 to find the infrared pulse repetition correction factor.
c) Multiply the CW MPE times the infrared pulse repetition correction factor to give the MPEPRF. Fill in the "MPE" block in the Repetitively Pulsed column.
Note for Repetitively Pulsed lasers: The simplified methods of Tables 2 to 4 use the Average Power to determine the
MPE in W/cm2. It is possible with other methods to use the Pulse Energy to determine the MPE per pulse in J/cm2. Onlyone of the two MPEs is required.
VISUAL EFFECT CALCUATIONS (for visible lasers only)
If the laser has no wavelengths in the visible range (400–700 nm), enter "N/A — non-visible laser" in these blocks and goto the next section (Beam Directions).
Appendix A For visible lasers, the Authority is concerned about beams that are eye-safe (below the MPE) but are bright enough to distract aircrews. In accordance with ICAO Recommendations (see Annex 14, Volume I — Aerodrome Design andOperations,, the Authority has therefore established Laser-beam Sensitive, Laser-beam Critical and Laser-beam FreeFlight Zones where aircraft should not be exposed to light above 100 µW/cm2, 5 µW/cm2, and 50 nW/cm2, respectively.
Because apparent brightness varies with wavelength — green is more visible than red or blue — a visual correction factorcan be applied if desired. This has the effect of allowing more power for red and blue beams than for green beams. For anyvisible laser, you must submit Visual Effect Calculations.
Pre-Corrected Power: The PCP is the power before applying any visual correction factor. The method used to determine
the PCP depends on which type of laser you are using:
Single Pulse (Column 1): Multiply the Pulse Energy (J) by 4, and enter in the form. Note.— This technique averages
the pulse's energy over the 0.25 sec maximum pulse duration and is a conservative approximation of the visual effect
of a pulse.
If you use less conservative calculations, you must document your methods and calculations.
Continuous Wave (Column 2): The Pre-Corrected Power is the same as the maximum power of the laser. Enter the
same value you previously filled out in the Power (W) block of the form.
Repetitively Pulsed (Column 3):
A) If you filled out the Power (W) block on the form, enter that value.
B) If you filled out the Pulse Energy (J) block on the form, multiply that value times the Pulse Repetition Frequency (Hz) to determine the average power.
Visual Correction Factor and Visually Corrected Power: The VCF takes into account the beam's apparent brightness,
which varies depending on wavelength. Once you find the VCF, you can then determine the VCP. You have a choice of
methods, depending on how precise you want to be:
1) For the simplest, most conservative analysis of a single- or multiple-wavelength beam: Assume there is no
correction factor at all — the laser is at maximum apparent brightness (VCF of 1.0). In the Visual Correction Factorblock of the form, enter "1.0 (assumed)" for the Visual Correction Factor. In the Visually Corrected Power block,enter the same value you filled out for the Pre-Corrected Power.
2) For a single-wavelength beam: To find the Visual Correction Factor, use Table 5. To find the Visually Corrected
Power, multiply the Visual Correction Factor by the Pre-Corrected Power. (An example calculation is provided atTable 5, example 1.) 3) For a beam with multiple wavelengths, choose one method:
A) Make a simplifying, conservative assumption. Use Table 5 to determine which wavelength has the largest Visual Correction Factor (is the most visible). Enter this in the Visual Correction Factor block of the form. To find theVisually Corrected Power, multiply this Visual Correction Factor by the Pre-Corrected Power of the laser (allwavelengths). Note.— You must attach data and calculations showing how you arrived at the Visually CorrectedPower. B) Analyse each wavelength separately, then sum them. First, determine the Pre-Corrected Power for each wavelength. Next, use Table 5 to find the Visual Correction Factor for each wavelength. Multiply eachwavelength's Pre-Corrected Power by its Visual Correction Factor, to find the Visually Corrected Power (VCP)for that wavelength. Add all the VCPs together to determine the total VCP. Enter the total VCP in the "VisuallyCorrected Power" block of the form. (An example calculation is provided in Table 5, example 2.) Note.— Youmust attach data and calculations showing how you arrived at the Visually Corrected Power. Manual on laser emitters and flight safety 3. BEAM DIRECTIONS
Provide the pointing directions of the beam projections for this configuration.
Azimuth: If the beam is moved horizontally during the operation, enter the movement range under "Azimuth"; for example,
"20 to 50 degrees". Make sure you give the range going clockwise; otherwise your data will be interpreted as directing the
beam everywhere but where you intend. Specify if azimuth is in true or magnetic readings.
Magnetic Variation: Provide the magnetic variation for the location if this is known (this must be done if you mark the
"Magnetic" check box or if you are using a compass as part of your control measures).
For some configurations, additional information about the beam direction may be needed. For example: lasers that are verywidely separated at the Geographic Location listed on page 1, or a laser used on an aircraft or spacecraft which is movingand/or shoots downwards. If this additional information is useful for the Authority to evaluate the proposal, then attach theinformation to this form.
There are four distances that are important in evaluating the safety of outdoor operations. Here are brief definitions: Nominal Ocular Hazard Distance (NOHD): The beam is an eye hazard (is above the MPE), from the laser source
to this distance.
Sensitive Zone Exposure Distance (SZED): The beam is bright enough to cause temporary vision impairment, from
the source to this distance. Beyond this distance, the beam is 100 µW/cm2 or less.
Critical Zone Exposure Distance (CZED): The beam is bright enough to cause a distraction interfering with critical
task performance, from the source to this distance. Beyond this distance, the beam is 5 µW/cm2 or less.
Laser-Free Exposure Distance (LFED): Beyond this distance, the beam is 50 nW/cm2 or less — dim enough that
it is not expected to cause a distraction.
For each of these four distances, it is important to know the distance directly along the beam (the Slant Range) as well asthe ground covered (the Horizontal Distance) and the altitude (the Vertical Distance). The diagram shows these threedistances.
Horizontal distance Appendix A NOMINAL OCULAR HAZARD DISTANCE
NOHD Slant Range: Use Equation 6.1 for Single Pulse, or for Repetitively Pulsed if you calculated the Pulse Energy and
MPEPRF. Use Equation 6.2 for Continuous Wave, or for Repetitively Pulsed if you calculated the Average Power and MPE.
Equation 6.1
SRNOHD = -------------- ϕ2 × MPEH Where: SRNOHD = NOHD Slant Range in feet Q = Pulse Energy (J)ϕ = Beam Divergence (mrad)MPEH = MPE per pulse in J/cm2 1366 = Conversion factor used to convert centimetres into feet and radians into milliradians Equation 6.2 SRNOHD = --------------
ϕ2 × MPEE Where:SRNOHD = NOHD Slant Range in feet ϕ = Beam Divergence (mrad) Φ = Power (W)MPEE = MPE in W/cm2 1366 = Conversion factor used to convert centimetres into feet and radians into milliradians Example: A 40-watt CW laser has a beam divergence of 1.5 milliradians
ϕ = 1.5 mrad
Φ = 40 WMPEE = 0.00254 (2.54 mW/cm2, from Table 2) Solve Equation 6.2: ------------------ = 9560804 = 3092 ft NOHD Horizontal Distance is the distance along the ground. Note that the horizontal distance uses the minimum elevation
angle. Calculate the horizontal distance using the equation:
HD = SRNOHD × cos(Minimum Elevation Angle) Where:HD = Horizontal distance along the ground. The units are the same as for the Slant Range. If SR is in feet, then HD willalso be in feet.
SRNOHD = NOHD Slant Range Minimum Elevation Angle = Data from "Minimum elevation angle" block on form.
Example: The NOHD Slant Range is 1000 feet, and the beam is elevated at 30 degrees above horizontal. The Horizontal
Distance along the ground is 1000 × cos(30), or 866 feet.
Manual on laser emitters and flight safety NOHD Vertical Distance is the distance above the ground. Note that the vertical distance uses the maximum elevation angle.
Calculate the vertical distance using the equation:
VD = SRNOHD × sin(Maximum Elevation Angle) Where:VD = Vertical distance (altitude). The units are the same as for the Slant Range. If SR is in feet, then VD will also be infeet.
SRNOHD = NOHD Slant Range Maximum Elevation Angle = Maximum elevation angle of laser beam as provided on form.
Example: The NOHD Slant Range is 1000 feet, and the beam is elevated at 30 degrees above horizontal. The Vertical
Distance (altitude) is 1000 × sin(30) or 500 feet.
Fill in this section only if one or more of the laser wavelengths are visible (in the range 400700 nm). If the laser is outside the visible range, enter "N/A — non-visible laser" in all SZED, CZED, and LFED blocks.
If the laser is visible, then perform the SZED, CZED, and LFED calculations below. Important: For some visible pulsed lasers, the SZED, CZED, and LFED may be calculated to be less (shorter distance) than
the NOHD. If this is the case, for safety reasons do not enter the distance numbers in the applicable block. Instead, you must
enter that the distance is "Less than NOHD". This is because in this case, the NOHD (eye-damage distance) would be the
most important for calculating safety distances and airspace to be protected.
SZED Slant Range: Use the following equation:
Equation 6.3
SRSZED = --ϕ---- × ΦVCP Where:SRSZED = SZED Slant Range ϕ = Beam Divergence (mrad) ΦVCP = Visually Corrected Power (from form) 3700 = Conversion factor used to convert centimetres into feet and radians into milliradians SZED Horizontal Distance: Use the following equation. For details, see the NOHD Horizontal Distance instructions above.
HD = SRSZED × cos(Minimum Elevation Angle) SZED Vertical Distance: Use the following equation. For details see the NOHD Vertical Distance instructions above.
VD = SRSZED × sin(Maximum Elevation Angle) Appendix A CZED Slant Range, Horizontal Distance and Vertical Distance: Multiply the SZED values above by 4.5. Example: If
SZED Slant Range was 5 000 feet, HD was 866 feet, and VD was 500 feet, then the CZED SR is 22 500 feet, HD is 3 897
feet and VD is 2 250 feet.
LFED Slant Range, Horizontal Distance and Vertical Distance: Multiply the SZED values above by 45.
List the method by which the calculations were performed.
Source note for equations: The equations above are derived from ANSI Z136.1 and have been re-expressed to a simpler
form as follows: Beam divergence (ϕ) is entered in milliradians, making the first ANSI fraction 1000/ϕ instead of 1/ϕ. The
radical (square root) sign is used instead of raising to a power of 0.5. Under the radical, the expression 4/π is reduced to
1.27, while beam diameter (a2) is not used since its contribution to the overall slant range distance is negligible. ANSI results
are in cm; to convert to feet, a conversion factor of 0.0328 is used (1 cm = 0.0328 ft). There are now two numeric constants,
1 000 (from the milliradians fraction) and 0.0328, which are multiplied into a single constant, 32.8, to give results in feet.
For results in cm, use "1 000" as the constant; for results in metres, use "10".
Note.— The assumption that a constant can be used to derive the CZED and LFED from the previously-calculated SZED is valid only if atmospheric attenuation is ignored. Should you be relying on atmospheric attentuation for a safety factor, youmust use a more detailed analysis which independently calculates these three Visual Effect Distances. Manual on laser emitters and flight safety Table 1. Single Pulse Selected Maximum Permissible Exposure (MPE) Limits
Reference American National InstituteStandard (ANSI)Z136 series Reference ANSI Z136 series 10–9 to 18 × 10–6 18 × 10–6 to 10 1.8 × t0.75 × 10–3 Reference ANSI Z136 series 10–9 to 18 × 10–6 0.5 × CA × 10–6 18 × 10–6 to 10 1.8 × CA × t0.75 × 10–3 0.64 × CA × 10–3 10 × CA × 10–3 Reference ANSI Z136 series 10–9 to 50 × 10–6 5.0 × CC × 10–6 50 × 10–6 to 10 9 × CC × t0.75 × 10–3 50 × CC × 10–3 Reference ANSI Z136 series Reference ANSI Z136 series Reference ANSI Z136 series Reference ANSI Z136 series To find CA:
For wavelength = 700 to 1050 nm, CA = 100.002 (wavelength – 700) Example 1: Laser wavelength is 850 nm; CA = 100.002(850 – 700) = 100.002*150 = 100.3 = 1.995
Example 2: Laser wavelength is 933 nm; CA = 100.002(933 – 700) = 100.002*233 = 100.466 = 2.924
To find CC:
For wavelength = 1050 to 1150 nm, CC = 1.0 For wavelength = 1150 to 1200 nm, CC = 100.018 (wavelength – 1150) For wavelength = 1200 to 1400 nm, CC = 8.0 Example 3: Laser wavelength is 1175 nm; CC = 100.018(1175 – 1150) = 100.018*25 = 100.45 = 2.8
To find t: "t" is the pulse duration in seconds.
Appendix A Table 2. CW Mode Maximum Permissible Exposure (MPE) Limits
Values are for selected wavelengths for unintentional viewing.
Reference American National Standards Institute ANSI (100.002(wavelength – 700))(1.01 × 10–3) (100.018(wavelength – 1150))(5 × 10–3) Example 1: Laser wavelength is visible; MPE = 0.00254 W/cm2
Example 2: Laser wavelength is 850 nm; MPE = (100.002(850 – 700))(1.01 × 10–3) = (100.002*150)(0.00101) = (100.3) × 0.00101
= 1.995 × 0.00101 = 0.002 W/cm2
Example 3: Laser wavelength is 1175 nm; MPE = (100.018(1175 – 1150))(5 × 10–3) = (100.018*25)(0.005) = (100.45) × 0.005
= 2.818 × 0.005 = 0.01409 W/cm2
"Unintentional viewing": Exposure durations used for unintentional viewing of a CW exposure are 0.25 seconds or shorter
for visible lasers, and 10 seconds or shorter for infrared lasers. (For visible light, it is assumed that within 0.25 seconds, the
person will blink or will move to avoid the light. For infrared, it is assumed that the laser will not stay in the same spot for
more than 10 seconds, due to normal body movement.)
Source: ANSI Z136.1 Table 5 for CW Exposure.
Manual on laser emitters and flight safety Table 3. Maximum Permissible Exposure — Pulse Repetition Frequency (MPEPRF) Limits for Visible Lasers
For unintentional viewing of repetitively pulsed visible (400–700 nm) laser light with pulse width between 1 ns and 18 µs.
If the laser's pulse repetition frequency falls between two table entries, use the more conservative (smaller) value of the tworesulting MPEPRF values.
Note.— This table for MPEPRF is based on repetitively pulsed lasers with a pulse width between 1 ns and 18 µs. These MPEPRF numbers can be used to estimate larger pulse widths, and will provide a conservative (safer) result. Not intended for scanning analysis: This table is intended for lasers that naturally emit repetitive pulses, such as Q-switched
lasers. It is not intended for analysing "scanned" pulses, caused by moving the beam quickly over a viewer or aircraft.
(Examples: graphics or beam patterns used in laser displays, or scanned patterns used for atmospheric analysis.) Pulses
resulting from scanning are often extremely variable in pulse width and duration, and thus require a more stringent analysis.
Appendix A Table 4. Correction Factors (MPEpulsed / MPEcw) for Repetitively Pulsed Infrared Lasers
Use to find MPEPRF of repetitively pulsed infrared (700–1 400 nm) laser light with pulse width between 1 ns and 18 µs.
*The MPE for lasers which operate at a PRF greater (faster) than 55 000 Hz for wavelengths 700–1 050 nm (or 22 000 Hzfor wavelengths 1 050–1 400 nm) is the same as for continuous wave lasers, so the correction factor is 1.
To find the MPE for repetitively pulsed infrared lasers, multiply the CW Mode MPE by a correction factor from this table.
If the laser's pulse repetition frequency falls between two table entries, use the more conservative (smaller) value of the tworesulting correction factors.
Example: A laser operating at a pulse repetition frequency (PRF) of 12 000 Hz emits infrared light at 850 nm. First, go to
Table 2 and find the CW Mode MPE for the 850 nm wavelength, which is 0.002 W/cm2 (see example 2 from Table 2). Next,
from the table above determine which of the right two columns should be used; in this case, the column labelled "For
wavelength 700–1 050 nm". The laser's PRF of 12 000 Hz falls between the 10 000 and 15 000 rows, so use the more
conservative (smaller) value of the 10 000 Hz PRF: 2.8 × 10–1. The correction factor is thus 0.28. Multiply this by the CW
Mode MPE found from Table 2 to get a MPEPRF of 0.28 × 0.002 W/cm2 = 0.00056 W/cm2 = 5.6 × 10–4 W/cm2.
Manual on laser emitters and flight safety Table 5. Visual Correction Factor for Visible Lasers
Use for visible lasers only (400–700 nm).
1.0 × 100– (VCF = 1) To find the Visually Corrected Power (VCP) for a specified wavelength, multiply the Visual Correction Factor (VCF) for thewavelength (from the table above) by the Average Power. If the laser's wavelength falls between two table entries, use themore conservative (larger) value of the two resulting VCFs.
Example 1: A frequency-doubled YAG laser emits 10 watts of 532 nm continuous wave light. From the table, 532 is between
530 and 540; use the more conservative (larger) Visual Correction Factor of 540 nm: 9.524 × 10–1. Multiply the VCF of
0.9524 by the Average Power of 10 watts to obtain the Visually Corrected Power of 9.524 watts.
Example 2: An 18-watt argon laser emits 10 watts of 514 nm light, and 8 watts of 488 nm light, both continuous wave.
Calculate each wavelength separately, then add the resulting Visually Corrected Powers together.
10 watts at 514 nm: From the table, 514 is between 510 and 520; use the more conservative (larger) VCF of 520 nm:
7.092 × 10–1. Multiply the VCF of 0.7092 by the Average Power of 10 watts to obtain the Visually Corrected Power of7.092 watts.
Appendix A 8 watts at 488 nm: From the table, 488 is between 480 and 490; use the more conservative (larger) VCF of 490 nm:
2.079 × 10–1. Multiply the VCF of 0.2079 by the Average Power of 8 watts to obtain the Visually Corrected Power of1.6632 watts.
Finally, add the two VCPs together: 7.092 + 1.6632 = 8.7552. The 18-watt laser in this example has a Visually Corrected Power of only 8.7552 watts. Note that the 10-watt YAG in Example 1 appears brighter to the eye (9.5 WVCP) than an 18-watt argon (8.8 WVCP). Source: The Visual Correction Factor used in this table (CF) is the CIE normalized efficiency photopic visual function curve
for a standard observer. The luminance (lm cm–2) is the measured irradiance multiplied by C F and 683. The effective irradiance is the actual (measured) irradiance multiplied by CF. The effective irradiance (W cm–2) multiplied by 683 lm W–1 is the illuminance (lm cm–2). The term "Visually Corrected Power" divided by the area of the laser beam is the "effective irradiance", as used in this document.
Appendix B
This form may be used by local ATC or airline authorities to report a suspected laser beam exposure. When completed, thereport should be forwarded to the competent authority as soon as possible for further investigation.
Position (pilot, co-pilot, controller, etc.) _ Phone _ Type of vision correction worn at time of incident (spectacles/contact lenses) _ Type of aircraft _ Aircraft ID or call _ Date and time of incident (UTC) _ Date and time report is being completed (UTC) _ Environmental factors: Weather conditions Ambient light level (day, night, sunlight, dawn, dusk, starlight, moonlight, etc.) Location of incident: Near (aerodrome/city/NAVAID) Radial and distance _ Phase of flight _ Type/name of approach or departure procedure _ Heading/approximate heading if in turn _ Altitude (AGL) (MSL) Aircraft bank and pitch angles _ Angle of incidence: Did the light hit your eye(s) directly or from the side? _ Manual on laser emitters and flight safety Light description: Nature of beam (constant/flicker/pulsed) Light source (stationary or moving) Do you feel you were intentionally tracked? _ Relative intensity (flashbulb, headlight, sunlight) Duration of exposure (seconds) Was the beam visible prior to the incident? Position of light source (relative to geographical feature or aircraft) Circle the window where the light entered the cockpit: Elevation of the beam from horizontal (degrees) Effect on individual: Describe visual*/psychological/physical effects _ Duration of visual effects (seconds/minutes/hours/days) Do you intend to seek medical attention? Note.— This is recommended if even minor symptoms were experienced. Effect on operational or cockpit procedures: * Examples of common visual effects: After-image. An image that remains in the visual field after an exposure to a bright light.
Blind spot. A temporary or permanent loss of vision of part of the visual field.
Flash-blindness. The inability to see (either temporarily or permanently) caused by bright light entering the eye and
persisting after the illumination has ceased.
Glare. A temporary disruption in vision caused by the presence of a bright light (such as an oncoming car's headlights)
within an individual's field of vision. Glare lasts only as long as the bright light is actually present within the individual's
field of vision.
This questionnaire may be filled out by the competent authority during interviews with persons exposed to laser beams. Thisinformation will be used to aid in any subsequent investigation and provide important medical and statistical data for thereview of regulatory and enforcement issues associated with new laser beam applications and threats to aviation safety. Thecompleted form should be forwarded to the appropriate aviation authority as soon as possible.
1. Did anyone else see the light beam? _ 2. What was the colour(s) of the light? Did the colour(s) change during the exposure? _ 3. Did the light come on suddenly, and did it become brighter as you approached it? 4. Was the light continuous or did it seem to flicker? _ If it flickered, how rapidly and regularly? _ 5. Did the light fill your cockpit or compartment? 6. How would you describe the brightness of the light? _ Was it equally bright in all areas or was it brighter in one area? _ 7. Did you attempt an evasive manoeuvre? _ If so, did the beam follow you as you tried to move away? How successful were you in avoiding it? _ 8. Do you know the source of the light emission? 9. Can you estimate how far away the light source was from your location? _ Was the source moving? _ 10. What was between the light source and your eyes — windscreen, glasses, contact lenses, etc.? _ Did any of these sustain damage by the light? _ 11. Was the light coming directly from its source or did it appear to be reflected off other surfaces? Were there multiple sources of light? 12. Did you look straight into the light beam or off to the side? 13. How long was the exposure? _ Did the light seem to track your path or was there incidental contact? 14. At what time of the day did the incident occur? _ 15. What was the visibility? What were the atmospheric conditions — clear, overcast, rainy, foggy, hazy, sunny? Manual on laser emitters and flight safety 16. What tasks were you performing when the exposure occurred? _ Did the light prevent or hamper you from doing those tasks, or was the light more of an annoyance? 17. What were the visual effects you experienced (after-image, blind spot, flash-blindness, glare*)? 18. How long did any symptoms you experienced from the exposure last? _ Are any symptoms (tearing, light sensitivity, headaches, etc.) still present? 19. Did you touch or rub your eyes at the time of the incident? _ 20. Did you have your eyes examined after the incident? _ If so, when and by whom? What were the results of this visit? 21. Did you report the incident? _ If so, to whom (ATC, medical personnel, safety officer, etc.) and when? * Examples of common visual effects: After-image. An image that remains in the visual field after an exposure to a bright light.
Blind spot. A temporary or permanent loss of vision of part of the visual field.
Flash-blindness. The inability to see (either temporarily or permanently) caused by bright light entering the eye and
persisting after the illumination has ceased.
Glare. A temporary disruption in vision caused by the presence of a bright light (such as an oncoming car's headlights)
within an individual's field of vision. Glare lasts only as long as the bright light is actually present within the individual's
field of vision.
Appendix C
The Amsler grid test is designed to detect defects in the central visual field of an eye, corresponding to retinal lesions assmall as 50 micrometres.
The chart below is sized to be viewed at a distance of 28–30 cm, the usual distance for reading tests. At this distance thetest will examine the central 20 degrees of the patient's field of vision for abnormalities, with each small square equivalentto 1 degree. Before using this chart: a) the refraction of the eye in question must be exactly corrected for this distance; b) the chart must be clearly and evenly illuminated as for a reading test; c) all artificial mydriasis and any ophthalmoscopy immediately before the examination must be avoided; and d) the other eye should be covered, preferably with an occluder.
Manual on laser emitters and flight safety While continually urging the patient to look steadily upon the central point, ask the following questions. Record the responsesand ask the patient to carefully draw any abnormal results on the grid chart. 1. Do you see the spot in the centre of the square chart? 2. Keeping your gaze fixed upon the spot in the centre, can you see the four corners of the big square? Can you also see the four sides of the square? In other words, can you see the whole square? 3. Keeping your gaze fixed upon the spot in the centre, do you see the network intact within the whole square? Are there any interruptions in the network of squares, such as holes or spots? Is it blurred in any place? If so, where? 4. Keeping your gaze fixed upon the spot in the centre, are both the horizontal and vertical lines straight and parallel? In other words, is every small square equal in size and perfectly regular? 5. Keeping your gaze fixed upon the spot in the centre, do you see any movement of certain lines? Is there any vibration or wavering, shining or colour tint? If so, where? 6. Keeping your gaze fixed upon the spot in the centre, at what distance from this point do you see the blur or distortion? How many small intact squares do you find between the blur or distortion and the centre point where your gaze isfixed? — END —

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Manual on LaserEmitters andFlight Safety Approved by the Secretary Generaland published under his authority First Edition — 2003 International Civil Aviation Organization Manual on LaserEmitters andFlight Safety Approved by the Secretary Generaland published under his authority First Edition — 2003