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
LASER HAZARD EVALUATION
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.
ACCESSIBLE EMISSION LIMIT (AEL)
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).
HAZARD DISTANCE (NOHD)
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
1n1 – ---------------------
With outdoor lasers, a buffer zone should be
–µ ⋅ NOHD
Q ⋅ 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
LASER BEAM BIOEFFECTS AND
THEIR HAZARDS TO FLIGHT OPERATIONS
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.
3.2 THE HAZARD
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.
3.5 THE EYE
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.
AND AIR OPERATIONS
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
AND TRAINING OF AIRCREW
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.
4.4 PREVENTATIVE PROCEDURES
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
5.1 GENERAL
"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, 5.3.1.1.
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
"5.3.1.2 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 5.3.1.2 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
COCKPIT ILLUMINATION MAY OCCUR BEYOND
of temporary laser activity
THESE DISTANCES.
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.
E) TEMPO NAV WRNG. LASER LIGHTSHOW WILL
FLASH-BLINDNESS OR COCKPIT ILLUMINATION
TAKE PLACE AT HARBOOERE PSN 563713N
MAY OCCUR BEYOND THESE DISTANCES.
0081130E. THE LASERBEAM MAY CAUSEBLINDNESS IF VIEWED WITHIN A VERTICAL
LASER RESEARCH WILL BE CONDUCTED AT (place,
DISTANCE OF 500FT AND HORIZONTAL DISTANCE
city, province or state, lat./long.), ON/FROM (dates),BETWEEN (times/UTC), AT AN ANGLE OF (degree),FROM THE SURFACE, PROJECTING UP TO (height)MSL AVOID AIRBORNE HAZARD BY (NM). THISLASER LIGHT BEAM MAY BE INJURIOUS TO
* More information about the NOTAM format can be found in
PILOTS/AIRCREW AND PASSENGERS EYES.
Chapter 5. Airspace safety
OF 0.5NM OF THE LIGHT SOURCE.
DISTANCE OF 5000FT AND HORIZONTAL DISTANCE
FLASHBLINDNESS OR COCKPIT ILLUMINATION
OF 2.5NM OF THE LIGHT SOURCE.
MAY OCCUR WITHIN A VERTICAL DISTANCE OF
FLASHBLINDNESS OR COCKPIT ILLUMINATION
8300FT AND A HORIZONTAL DISTANCE OF 8NM
MAY OCCUR WITHIN A VERTICAL DISTANCE OF
5300FT AND A HORIZONTAL DISTANCE OF 8NM
F) GNDG) 8300FT MSL
XXXXX/XX NOTAMNQ) EKDK/QWXXX/V/B/W/000/103/A) EKDK B) 0006091900 C) 0006102200
5.6 INCIDENT-REPORTING REQUIREMENTS
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
DOCUMENTATION OF INCIDENTS
AFTER SUSPECTED LASER BEAM ILLUMINATION
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
MEDICAL EXAMINATION FOLLOWING
SUSPECTED LASER BEAM ILLUMINATION
7.1 GENERAL
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
NOTICE OF PROPOSAL TO CONDUCT
OUTDOOR LASER OPERATION(S)
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
2. BRIEF DESCRIPTION OF OPERATION
3. ON-SITE OPERATION INFORMATION
BRIEF DESCRIPTION OF CONTROL MEASURES
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)
STATEMENT OF ACCURACY
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)
MAXIMUM PERMISSIBLE EXPOSURE (MPE) CALCULATIONS (will be used to calculate NOHD)
MPE
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)
VISUAL EFFECT DISTANCES
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)
5. CALCULATION METHOD
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.
1. GENERAL INFORMATION
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.
2. BRIEF DESCRIPTION OF OPERATION
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.
3. ON-SITE OPERATION INFORMATION
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.
BRIEF DESCRIPTION OF CONTROL MEASURES
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.
5. DESIGNATED CONTACT PERSON
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.
STATEMENT OF ACCURACY
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.
INSTRUCTIONS FOR FILLING OUT LASER CONFIGURATION FORM (page 2)
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.)
1. CONFIGURATION 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.
Appendix A
2. BEAM CHARACTERISTICS AND CALCULATIONS
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
column.
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, 5.3.1.2), 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.
4. DISTANCES CALCULATED FROM ABOVE DATA
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
Given:
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.
VISUAL EFFECT DISTANCES
Fill in this section only if one or more of the laser wavelengths are visible (in the range 400–700 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.
5. CALCULATION METHOD
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.
Frequency
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
SUSPECTED LASER BEAM INCIDENT REPORT AND
SUSPECTED LASER BEAM EXPOSURE QUESTIONNAIRE
SUSPECTED LASER BEAM INCIDENT REPORT
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.
— — — — — — — —
Appendix B
SUSPECTED LASER BEAM EXPOSURE QUESTIONNAIRE
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
AMSLER GRID TESTING PROCEDURE
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