Laser Safety Training
Environmental Health and Life Safety
(EHLS)
713-743-5858
http://www.uh.edu/ehls
Course
This course provides
Basic understanding of lasers and how they function
General understanding of Laser hazards
General instructions on how to work safely with lasers,
and how to be protected from potentially harmful
radiation
An overall safety awareness in laser use labs.
Based on the Texas Regulations for the Control of
Radiation
This course covers basic laser radiation safety, physics,
and biology and is not intended to be exhaustive on
these subjects.
LASER LIGHT PROPERTIES
1
Laser Light Properties
The light output of a laser differs from the
output of ordinary light sources. Four
properties characterize the laser’s output:
Small Divergence
Monochromatic
Coherence
High Intensity
Laser Light Properties
Divergence
When light emerges from the laser, it does not diverge
(spread) very much at all. Thus the energy is not greatly
dissipated as the beam travels.
Monochromatic
Laser Light is very close to being monochromatic. The
term “monochromatic” means one color, or one
wavelength, of light. Actually, very few lasers produce
only one wavelength of light.
Laser Light Properties
Coherence
Coherence is a term used to describe particular relationships between two
wave forms. Two waves with the same frequency, phase, amplitude, and
direction are termed spatially coherent.
High Intensity
Laser light can be very intense. Energy is a measure of capacity for doing
work and is measured in joules (J) in the metric system. Power is the rate
at which work is being done and is measured in watts (W).
1 joule = 1 watt–second
1 watt = 1 joule/second
A laser capable of emitting 10 joules per second can be termed a 10 watt
laser. If the same 10 joules are emitted as a single pulse of 1/100th second
duration, then the laser can be termed a 1,000 watt laser.
Irradiance = W/cm2 Radiant Exposure = J/cm2
2
FUNDAMENTAL DEFINITIONS
Definitions
Maximum Permissible Exposure Limit (MPE) – the
level of laser radiation to which an unprotected
person may be exposed without adverse biological
changes in the eye or skin
Nominal Hazard Zone (NHZ) – the space within
which the level of the direct, reflected, or scattered
radiation may exceed the applicable MPE.
Exposure levels beyond the boundary of the NHZ
are below the appropriate MPE.
Definitions
CW Laser – a continuous wave laser whose output persists
for a relatively long interrupted time interval, while the
laser is turned on.
Pulsed Laser – a pulsed laser whose output occurs in
short, interrupted time intervals, in contrast to a CW
laser.
3
Definitions
Beam Divergence – the increase in beam diameter with
distance measured from the aperture of the laser.
Power Density – A term used to denote the power emitted
per unit area per solid angle (watts per square
centimeter per steradian). It is equivalent to the
radiometric term “irradiance”.
BASICS OF
LASERS AND LASER LIGHT
L ight
A mplification by
S timulated
E mission of
R adiation
Thus the laser is a device which produces and amplifies light
Laser-Professionals.com
Laser Components
Three components are necessary for laser
construction and operation
An active lasing medium
An input energy source (Called a “Pump”)
An optical Resonator
4
LASER COMPONENTS-Summary
Optical Resonator
Output
Beam
Active
Medium
High Reflectance
Mirror (HR)
Output Coupler
Mirror (OC)
Excitation
Mechanism
All lasers have the same basic design.
Lasing Medium
Lasers can be classified according to the state of
the lasing media
Solid state lasers employ a lasing material
distributed in a solid matrix
Ex. Ruby laser
Gas lasers use a gas or mixture of gases within
a glass tube
Ex. HeNe, CO2, Argon, and Krypton
Change energy levels
Lasing Medium
Liquid lasers are usually a complex organic dye
with the most versatile feature of “tunability”; and
proper choice of the dye and its concentration
allows light production at almost any wavelength in
or near the visible spectrum
Ex. Dye laser
5
Energy input source-Pumps
Laser action can occur only when a population inversion
has been established in the lasing medium. Several
methods of pumping are commonly used.
Optical pumping is employed in solid state and liquid
lasers. Xenon flashtubes are commonly used for
solid state lasers and liquid lasers usually are
pumped by a beam from another solid state laser.
Electron collision pumping is utilized in gas lasers.
An electrical discharge is sent through the gas-filled
tube.
Optical Cavity
Once the lasing medium has been pumped and a
population inversion obtained, lasing action may begin.
Without an optical cavity the direction of beam
propagation would be produced in all directions leading
to super-radiant lasing.
The beam of propagation can be controlled by placing
the lasing medium in an optical cavity formed by two
reflectors facing each other along a central axis.
Photon beams which are produced along that cavity are
reflected 1800 at each reflection and travel once more
through the lasing medium causing more stimulated
emission. Thus the beam grows in magnitude with each
traverse of the lasing medium.
Optical Cavity
• Reflectors may consist of plane mirrors,
curved mirrors, or prisms.
• Reflectors are not 100% reflective,
• Some photons may be lost by transmission
through the mirrors with each passage.
• With continuous pumping, a state of
equilibrium will soon be reached
• between the number of photons produced by
atoms raised to the excited state and the
number of photons emitted and lost.
• Result: a continuous laser output, usually
used only with low power input levels.
6
Higher power inputs usually are achieved
in the form of a pulse form.
• One of the mirrors in the system is usually
made more transparent than the other and
the output, pulsed or continuous, is
obtained through the reflector.
A Q-switch is a device which interrupts the
optical cavity for a short period of time
during pumping. Q-switching is used to
produce an exceptionally high-power
output pulse.
All lasers have the same basic design.
• The active medium contains the atoms that produce
laser light by stimulated emission - This can be a solid
crystal, a gas, a semiconductor junction, or a liquid.
• The excitation mechanism is the source of energy that
excites the atoms to the proper energy level for
stimulated emission to occur.
• Solid state lasers use optical sources for excitation; gas
lasers use electrical excitation.
• The active medium and excitation mechanism together
form an optical amplifier. Laser light entering one end of
the amplifier will be amplified by stimulated emission as
it travels through the active medium.
• The optical resonator is a pair of mirrors at the ends of
the active medium. These mirrors are aligned to reflect
the laser light back and forth through the active medium.
• The output coupler has a lower reflectance and allows
some of the laser light to pass through to form the output
beam.
• The fraction of the light that is allowed to pass through
the output coupler depends on the type of laser.
7
VIDEO
Slides Covered or Supplemental
to Video
Laser Spectrum
•
Lasers operate in the ultraviolet, visible, near infrared, and far
infrared regions of the spectrum.
•
Visible light has a wavelength range of 400 – 700 nm
• It and can be seen by the eye.
• The fact that you can see this light helps you avoid hazardous
exposures.
•
The near infrared has a range of 700 – 1400 nm.
• It cannot be seen because the retinal receptors do not work at
these wavelengths. However, the optical elements of the eye
transmit the NIR and focus these wavelengths on the retina.
• This produces an invisible retinal hazard and the potential for
serious eye injury in the near IR.
• The most stringent laser safety precautions are required in this
wavelength range. It also contains several of the most useful
lasers.
8
Ultraviolet – below 400 nm
Ocular Focus – 400 to 1400 nm
retinal hazards which contain two distinct subranges
400 to 700 nm – visible portion of spectrum and
provides the light the eye uses to see with
Colors Blue
450 nm
Green 500 nm
Yellow 550 nm
Orange 600 nm
Red
700 nm
700 to 1400 nm – also permitted by ocular components
except that the retina, which also absorbs this range of
wavelengths does not “see” them (invisible)
Infrared – above 1400 mm
UV and IR wavelengths are not transmitted through the
cornea and other exterior parts of the eye. Not focused
on the retina and therefore magnification of laser light
energy is not possible
LASER SPECTRUM
Gamma Rays
10-13
10-12
10-11
X-Rays
10-10
10-9
Ultra- Visible
violet
10-8
10-7
Infrared
10-6
10-5
Microwaves
10-4
10-3
10-2
1200
1300
Radar
waves
10-1
TV
waves
1
10
Radio
waves
102
Wavelength (m)
LASERS
Retinal Hazard Region
Ultraviolet
200
300
Visible
400
500
600
Near Infrared
700
800
900
1000
1100
Far Infrared
1400
1500
10600
Wavelength (nm)
ArF
193
XeCl
308
KrF
248
Ar
488/515
HeNe Ruby
633 694
2
Alexandrite GaAs
Nd:YAG
755
905
532
Nd:YAG
1064
Communication CO2
10600
Diode
1550
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Laser Classification
ANSI Z136.1 emphasizes that “It must be recognized that this
classification scheme relates specifically to the laser device and its
potential hazard, based on operating characteristics.
However, the conditions under which the laser is used, the level of
safety training of persons using the laser, and other environmental and
personnel factors are important considerations in determining the full
extent of safety control measures.”
Beam Reflections – laser beams are reflected to some extent from any
surface contacted. Essentially all reflections of laser beams result in
spreading the beam or beam divergence
Specular – If reflecting surface is shiny like a mirror
Diffuse – If reflecting surface is not shiny
9
Laser Classes; ANSI Z136.1
(2007)
Class 1 (I)
Class I M
Class 2 (II)
Class 2 M
Class 3 R (Class 3a)
Class 3B
Class 4
Class 1
Class 1 - Exempt Lasers
– Produce levels of radiation that have not been found
to cause biological damage
– This group is normally limited to gallium-arsenide
lasers or certain enclosed lasers
– Incorporated into consumer or office machine
equipment
Safety Precautions
– No laser specific rules, however general lab safety
rules still apply
Class 2
Class 2 - Low power and low risk
– Produce radiation that could cause eye damage after
direct, long term exposure
– Hazardous only if viewer overcomes natural aversion
response to bright light and continuously stares into
source. Like blinding oneself by forcing oneself to
stare at the sun for more than 10 to 20 seconds.
– Example lasers: grocery laser scanners
Safety Precautions
– Never permit a person to stare into the laser source
– Never point the laser at an individuals eye
10
Class 3 (A and R)
Class 3 - Moderate Risk or Medium Power
– Produce radiation powerful enough to injure human
tissue with 1 short exposure to the direct beam or its
direct reflections off a shiny surface.
– However, not capable of causing serious skin injury or
hazardous diffuse reflections under normal use.
Class 3B
Safety Precautions for Class 3B
– Do not aim the laser at an individuals eye
– Permit only experienced personnel to operate the
laser
– Enclose the beam path as much as possible.
– Even a transparent enclosure will prevent individuals
from placing their head or reflecting objects within the
beam path
– Termination should be used at the end of the useful
paths of the direct and any secondary beams
– Operate the laser only in a restricted area
Class 3B Continued
– Place the laser beam path well above or well below the
eye level of any sitting or standing observers whenever
possible
– The laser should be mounted firmly to assure that the
beam travels only along its intended path
– Always use proper laser eye protection for the direct
beam or a specular reflection
– Key switch to prevent tampering by unauthorized
individuals
– Remove all unnecessary mirror-like surfaces from within
the vicinity of the laser beam path
11
Class 4
Class 4 - High Power, High risk of injury and can cause
combustion of flammable materials.
– May also cause diffuse reflections that are eye hazards
and may also cause serious skin injury from direct
exposure
Safety Precautions
– Class 3B safety precautions and;
– Should only be operated within a localized enclosure or in
a controlled workplace
– If complete local enclosure is not possible, Interlocking of
room
– Eye wear is needed for all individuals working within the
controlled area
– Backstops should be diffusely reflecting - fire resistant
target materials
Laser Radiation Hazards
LASER BEAM INJURIES
High power lasers can cause skin burns.
E.g. CO2 Laser used for medical applications
Lasers can cause severe eye injuries
resulting in permanent vision loss.
12
CAUSES OF LASER ACCIDENTS
Studies of laser accidents have shown that there are usually
several contributing factors. The following are common
causes of laser injuries:
• Inadequate training of laser personnel
• Alignment performed without adequate procedures
• Failure to block beams or stray reflections
• Failure to wear eye protection in hazardous situations
• Failure to follow approved standard operating
procedures or safe work practices
TYPES OF LASER EYE EXPOSURE
INTRABEAM
VIEWING
EYE
LASER
SPECULAR
REFLECTION
LASER
DIFFUSE
REFLECTION
LASER
REFLECTED
BEAM
MIRROR
SCATTERED
LIGHT
ROUGH
SURFACE
Biological Effects
Laser light can cause damage to living
tissue. The extent of damage to living
tissue caused by laser light depends
primarily upon:
Frequency of the light
Power density of the beam
Exposure time
Type of tissue struck by the beam
13
Biological Effects
Damage can occur through 2 mechanisms of interactions:
Thermal Effect
Absorbed energy produces heat
The rapid rise in temperature can denature the protein
materials of tissue, much as an egg white is coagulated when
cooked
Light absorption in tissue is not homogeneous and the thermal
stress is greatest around those portions of tissue that are the
most efficient absorbers
Elastic or Acoustic Transient or Pressure Wave
Mechanical compression wave, can rip and tear tissue
Biological Effects
Hazards
Laser light is usually only a hazard to those tissues
through which the light beam can penetrate and which
will absorb the wavelength involved
We are concerned primarily with two organs, the
eyes and the skin
Of the two, the eye is often far more vulnerable to injury
than the skin from visible and near-infrared laser
radiation, thus it is considered the organ most important
to protect from all wavelengths of laser radiation
Biological Effects
Skin Anatomy
The other area of concern is the skin. It is not as
sensitive as the eye, and if damaged, most injuries are
more easily repaired. However it too is subject to great
damage from laser impact when energy densities
approach several J/cm2.
The skin is not a homogeneous mixture. It is a
specialized, layered structure with numerous odd
inclusions, such as blood vessels and hair follicles.
The skin is relatively transparent to laser light and
absorption in the skin occurs, for the most part, in the
pigment granules and the blood vessels.
14
Thermal & Photochemical
Thermal-injuries are caused by heating of
the tissue as a result of the absorption of
laser energy
– Micro-cavitation-a type of thermal effect that
occurs when a short laser pulse is focused
onto the retina (can ruptures blood vessels in the retina)
Photochemical- injuries occur because
high energy photons break molecular
bonds inside living cells
SKIN BURN FROM CO2 LASER EXPOSURE
Accidental exposure to partial reflection of 2000 W CO2 laser beam
from metal surface during cutting
Other Photochemical effects
Other UV photochemical effects include
– “welder’s flash” (Phtokeratitis),
– cataracts,
– and skin cancer from long term low level
exposures.
15
Biological Effects
Eye Damage
The portion of the eye affected by the laser is dependent upon the
wavelength of the light.
Injury to the anterior portion of the eye
Cornea is sensitive to very short wavelengths UV and long
wavelengths in the IR range such as the 10,600 nm output of
carbon dioxide lasers
Other anterior structures such as the iris and lens are
sensitive to wavelengths between 315 and 400 nm.
Important note to remember is that exposures to the lens one
day may cause effects which will not become evident for many
years
Biological Effects
Biological Effects
Injury to posterior portion of eye
The retina can be damaged by lasers that operate in the visible
and invisible range such as:
Ruby – 694.3 nm
HeNe – 632.8 nm
Kr – 488-650 nm
Ar – 455-529 nm
Nd:YAG – 1064 nm, 532 nm
Ti:Sapphire – 650-1100 nm
He:Ne – 543-1152 nm
16
25 
THERMAL BURNS
ON
PRIMATE RETINA
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Photo courtesy of U S Air Force
EYE INJURY BY Q-SWITCHED LASER
Retinal Injury produced by four pulses from a Nd:YAG laser range finder.
Photo courtesy of U S Army Center for Health Promotion and Preventive Medicine
MULTIPLE PULSE RETINAL INJURY
17
Eye Protection
Protective eyewear shall be worn by all individuals with access to Class
3b and/or Class 4 levels of laser radiation.
Protective eyewear devices shall provide a comfortable and appropriate
fit all around the area of the eye; be in proper condition to ensure the
optical filter(s) and holder provide the required optical density or greater
at the desired wavelengths and retain all protective properties during its
use; be suitable for the specific wavelength of the laser and be of
optical density adequate for the energy involved; have the optical
density or densities and associated wavelengths(s) permanently
labeled on the filters or eyewear; and examined, at intervals not to
exceed 12 months, to ensure the reliability of the protective filters and
integrity of the protective filter frames.
Unreliable eyewear shall be discarded.
Laser Eyewear
Laser Eyewear
Laser eyewear is not for direct viewing.
>10 W power, eyewear will protect for
about 3 seconds. >100 W power will burn
the eyewear almost instantly.
EXTREME EYE SAFETY HAZARD,
uncoated polycarbonate transmits 10,600
nm CO2 laser light (ABSOLUTELY will
NOT protect the eyes): Acrylic (most
versions) stops 10,600 nm wavelength.
18
Skin Protection
When there is a possibility of exposure to
laser radiation that exceeds the MPE limits
for the skin, the registrant shall require the
appropriate use of protective gloves, clothing,
or shields.
Non Beam Laser Radiation
Hazards
Non Beam Hazards
– Chemical Hazards
– Physical Hazards
– Biological Hazards
– Human Factors
19
Non-Beam Hazards
Mostly from High powered Lasers
– Applications like material processing, medical
procedures, etc give rise to respiratory
hazards
– Laser welding, cutting and drilling procedures
generate potentially hazardous fumes and
vapors
– Plume from laser tissue interactions- hazard
during laser surgery
Non-Beam Hazards Continued
Electrical shock/electrocution
– Use proper controls when working with
dangerous high voltage
Noise hazards up to 140 dB
Cryogenic coolants e.g. nitrogen
Non-Beam Hazards Continued
 LGAC (Laser generated airborne contaminants)
• Benzene, Toluene, HCl, Naphthalene, carbon
monoxide, Fluorine, etc.
• Aerosols – Metal Oxides, Organic, Biologicals
Dust, mist, fume, fog, smoke, smog,
 Laser Dyes and Solvents
Dyes – some are toxic, mutagenic
Solvents – irritation, anesthetics, maybe
flammable
Potential for contaminated parts
20
Non-Beam Hazards Continued
Collateral and Plazma Radiation
• X-ray – may require shieling if above 15kV: Thyratron
switched in pulse lasers and free electron lasers
• UV – Plasma radiation, from material processing on
metals: Nd:YAG and CO2
• Visible – brightness, blue light hazards(possible damage
to retina): Nd:YAG and CO2
• Infrared – Interact with stainless steel and generate
bright blue wavelength (plasma)
Non-Beam Hazards Continued
• Radio Frequency – Pulsed Nd:YAG and CO2
• Extremely Low Frequency – Pulsed Nd:YAG, class IIIR
HeNe
Fire
• Normally limited to combustion of flammable materials
such as paper by CW lasers operating with an output
greater than 0.5 W, class 4
• Class IIIB laser will ignite dust in dusty environment
• Depends on enclosure materials, construction materials,
target materials, laser gases, vapors, LGAC
Non-Beam Hazards Continued
Explosion
• May exist due to high pressure arc lamps, filament
lamps, target, dust collection explosion, etc.
21
Non-Beam Hazards Continued
Compressed Gas Cylinders
•
•
•
•
•
•
•
•
•
Do not drop cylinders or permit them to strike each other violently
Where caps are provided for valve protection, keep such caps in
place except when the cylinders are in use
Do not force connections that do not fit
Never lubricate, modify, force, or tamper with a cylinder valve
Chain or strap cylinders securely in place so they will not fall over
When cylinders are not in use, keep valves tightly closed
Handle empty cylinders as though they were full; Keep them
chained or strapped, and store them away from full cylinders
Transport cylinders with cap in place and use a hand truck to which
they can be strapped or chained
Make sure cylinders are labeled to identify the contents
Know the identity of the gas you are using, and be familiar with its
properties
Break
10 minutes
22
Laser Safety Standards and
Regulations
Regulatory Agencies/Standards
• Texas Department of State Health Services (DSHS)
• [Regulates university of Houston through a
Certificate of Laser Registration]
•
Food and Drug Administration (FDA)
•
The American National Standard for Safe Use of Lasers (ANSI Z136.1)
• This is a VOLUNTARY Standard that applies to the use of lasers.
• It is “recognized by” : The Occupational Safety and Health
Administration (OSHA)
•
IEC 60825 International Standard
Laser Regulations
Radiation Safety Requirements for Class 3b and 4 Lasers
• Individuals shall not use lasers on humans unless under the
supervision of a licensed practitioner of the healing arts and unless
the use of lasers is within the scope of practice of their professional
license.
• Individuals shall not be intentionally exposed to radiation above the
maximum permissible exposure (MPE) unless such exposure has
been authorized by a licensed practitioner of the healing arts.
• Exposure of an individual for training, demonstration or other non-
healing arts purposes is prohibited unless authorized by a licensed
practitioner of the healing arts.
• Exposure of an individual for the purpose of healing arts screening is
prohibited, except as authorized by the Texas Department of State
Health Services.
23
Laser Regulations
• Exposure of an individual for the purpose of research is
prohibited, except as authorized in research studies.
• Any research using radiation producing devices on
humans must be approved by an Institutional Review
Board (IRB) as required by the Code of Federal
Regulations.
• The IRB must include at least one practitioner of the
healing arts to direct use of the laser.
• These requirements apply to lasers that operate at
wavelengths between 180 nm and 1 mm.
Registration Requirements
The registrant shall notify the agency in writing within 30
days of any increase in the number of lasers authorized by
the Registration.
An application for healing arts shall be signed by a licensed
practitioner of the healing arts.
An application for veterinary medicine shall be signed by a
licensed veterinarian.
Each new use of a Class 3b or Class 4 laser in the healing
arts or for animal use shall be submitted to the agency
within 30 days after beginning operation of the laser.
Registration Continued
No person shall make, sell, lease, transfer, or lend lasers
unless such machines and equipment, when properly
placed in operation and used, shall meet the applicable
requirements.
Each registrant shall inventory all Class 3b and Class 4
lasers in their possession at an interval not to exceed
one year.
The inventory shall be maintained for inspection and
include:
Manufacturer’s Name
Model and Serial Number of the laser
Description of the laser
Location of the laser
24
Registration Continued
The Registrant shall maintain records of receipt, transfer,
and disposal of Class 3b and Class 4 lasers for
inspection to include:
Manufacturer’s Name
Model and Serial Number of the laser
Date of receipt, transfer, and disposal
Name and address of person laser(s)
received from, transferred to, or
disposed by
Name of individual recording the information
Laser Regulations
Each registrant or user of any laser shall not permit any
individual to be exposed to levels of laser or collateral
radiation higher than the Maximum Permissible Exposure
(MPE) limits.
Personnel operating each laser shall be provided with
written instructions for safe use, including clear warnings
and precautions to avoid possible exposure to laser or
collateral radiation in excess of the MPE.
Engineering Controls
Measures necessary for controlling laser hazards
normally concentrate upon making the beam path
inaccessible, such as enclosing the laser in a box or
controlled room to prevent unauthorized access.
As this is not always possible, other Administrative and
Engineering Controls are used to lessen the possibility of
injury.
The Safety Procedures necessary for any laser
operation vary with 3 aspects:
– Laser hazard classification
– Environment where the laser is used (outside vs. inside a
controlled area)
– People operating or within the vicinity of the laser beam (Desks
in lab)
25
Performance Standards
(Regulatory)
Engineering Controls
Protective Housing
Each laser shall have a protective housing that prevents
human access during the operation of the laser and
collateral radiation that exceeds the limits of Class 1.
Safety Interlocks
A safety interlock, that shall ensure that radiation is not
accessible above the MPE limits, shall be provided for
any portion of the protective housing that by design can
be removed or displaced during normal operation or
maintenance, and thereby allows access to radiation
above the MPE limits.
Adjustment during operation, service, testing, or
maintenance of a laser containing interlocks shall not
cause the interlocks to become inoperative or the
radiation to exceed MPE limits outside protective
housing except where a laser controlled area is
established.
Safety Interlocks (pulsed laser)
For pulsed lasers, interlocks shall be designed so as to prevent firing
of the laser; for example, by dumping the stored energy into a
dummy load.
For continuous wave lasers, the interlocks shall turn off the power
supply or interrupt the beam; for example, by means of shutters.
An interlock shall not allow automatic accessibility of radiation
emission above MPE limits when the interlock is closed.
Either multiple safety interlocks or a means to preclude removal or
displacement of the interlocked portion of the protective housing
upon interlock failure shall be provided, if failure of a single interlock
would allow human access to high levels of laser radiation.
26
Viewing Optics and Windows
All viewing ports, viewing optics, or display screens included as an
integral part of an enclosed laser or laser product shall incorporate
suitable means, such as interlocks, filters, or attenuators, to maintain
the laser radiation at the viewing position at or below the applicable
MPE under any conditions of operation of the laser
All collecting optics, such as lenses, telescopes, microscopes,
endoscopes, etc., intended for viewing use with a laser shall
incorporate suitable means, such as interlocks, filters, or attenuators, to
maintain the laser radiation transmitted through the collecting optics to
levels at or below the appropriate MPE.
Normal or prescription eyewear is not considered collecting optics.
Warning Systems
Each class 3b, or 4 laser or laser product shall provide visual or audible
indication during the emission of accessible laser radiation. For class
3b lasers and class 4 lasers, this indication shall be sufficient prior to
emission of such radiation to allow appropriate action to avoid
exposure.
Any visible indicator shall be clearly visible through protective eyewear
designed specifically for the wavelength(s) of the emitted laser
radiation.
If the laser and laser energy source are housed separately and can be
operated at a separation distance of greater than two meters, both
laser and laser energy source shall incorporate visual or audible
indicators.
The visual indicators shall be positioned so that viewing does not
require human access to laser radiation in excess of the MPE.
Controlled Area
For class 3b lasers or class 4 lasers, a controlled area
shall be established when exposure to the laser radiation
in excess of the MPE or the collateral limits is possible.
Each controlled area shall be posted by proper laser
signage and access to the controlled area shall be
restricted.
27
Indoor controlled areas
For Class 4 indoor controlled areas, latches, interlocks, or other appropriate
means shall be used to prevent unauthorized entry into controlled areas.
Where safety latches or interlocks are not feasible or are inappropriate, for
example during medical procedures, the following shall apply:
All authorized personnel shall be trained in laser safety and
appropriate personnel protective equipment shall be provided upon
entry;
A door blocking barrier, screen, or curtains shall be used to block,
screen, or attenuate the laser radiation at the entryway.
The level at the exterior of these devices shall not exceed the applicable
MPE, nor shall personnel experience any exposure above the MPE
immediately upon entry.
At the entryway there shall be a visible or audible signal indicating that the
laser is energized and operating at Class 4 levels.
Class 4 Indoor Controlled Area
For Class 4 indoor controlled areas, during tests requiring continuous
operation, the individual in charge of the controlled area shall be
permitted to momentarily override the safety interlocks to allow
access to other authorized personnel if it is clearly evident that there
is no optical radiation at the point of entry, and if necessary
protective devices are being worn by the entering personnel.
For Class 4 indoor controlled areas, optical paths from an indoor facility
shall be controlled in such a manner as to reduce the transmitted
values of the laser radiation to levels at or below the appropriate
MPE and the collateral limits.
Temporary Controlled Area
When the removal of panels or protective covers and/or
overriding the interlocks becomes necessary, such as for
servicing, testing, or maintenance, and accessible laser
radiation exceeds the MPE and the collateral limits, a
temporary controlled area shall be established.
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Nominal Hazard Zone (NHZ)
Where applicable, in the presence of unenclosed Class
3b and Class 4 laser beam paths an NHZ shall be
established.
If the beam of an unenclosed Class 3b and Class 4 laser
is contained within a region by adequate control
measures to protect personnel from exposure to levels of
radiation above the appropriate MPE, that region may be
considered to be the NHZ.
Key Control
Each Class 3b and Class 4 laser shall incorporate a keyactuated or computer-actuated master control.
The key shall be removable and the Class 3b and Class
4 laser shall not be operable when the key is removed.
When not being prepared for operation or is unattended,
the key will be removed from the device and stored in a
location away from the machine.
Additional Requirements for
Safe Operation
Infrared Laser
The beam from an infrared laser shall be terminated in a
fire-resistant material where necessary.
Inspection intervals of absorbent material and actions to
be taken in the event or evidence of degradation shall be
specified in the operating and safety procedures.
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Radiation Signage and Postings
Radiation Signage and Postings
Radiation Signage and Postings
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Radiation Signage and Postings
Radiation Signage and Postings
Radiation Signage and Postings
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Radiation Signage and Postings
Audits/Inspections
Lasers inspections are conducted by Radiation Safety to ensure
regulatory compliance at intervals not to exceed 12 months.
The inspections include a determination that all laser protective devices
are labeled correctly, and functioning within the design specifications,
and properly chosen for lasers in use; a determination that all warning
devices are functioning within their design specifications; a
determination that the controlled area is properly controlled and posted
with accurate warning signs; a re-evaluation of potential hazards from
surfaces that may be associated with beam paths; and additional
surveys that may be required to evaluate the primary and collateral
radiation hazard incident to the use of lasers.
Records & Documentation
Records
Radiation Safety will maintain compliance records for regulatory review.
Applicable records must be submitted to Radiation Safety upon request.
Injury or Medical Event
The Laser Safety Officer shall immediately seek appropriate medical attention for
the individual and notify the agency by telephone of any injury involving a laser
possessed by the registrant, other than intentional exposure of patients for
medical purposes, that has or may have caused an injury to an individual that
involves the partial or total loss of sight in either eye; or an injury to an individual
that involves perforation of the skin or other serious injury exclusive of eye injury.
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Regulatory Reporting
The Laser Safety Officer shall, within 24 hours of discovery of an injury,
report to the agency each injury involving any laser possessed by the
registrant, other than intentional exposure of patients for medical
purposes, that may have caused, or threatens to cause, an exposure to
an individual with second or third-degree burns to the skin or potential
injury and partial loss of sight.
The Laser Safety Officer shall make a report in writing to the agency
within 30 days and a notice to the individual shall be transmitted at the
same time.
The LSO shall also notify the agency of any medical event involving a
patient as required.
UNIVERSITY OF HOUSTON
RADIATION SAFETY PROGRAM
Purpose
Protection of the university population, general
public, and environment against radiation
hazards associated with UH’s possession, use,
transportation, and disposal of radioactive
material.
Provide for compliance with TDSHS and other
applicable radiation protection regulations.
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Laser Safety Manual
Purpose
The purpose of the Laser Safety Manual is to assist personnel,
students, and management in complying with the State Radiation
Regulations and the Laser Safety Program.
Intent
This Laser Safety Manual is not intended to be an exhaustive or fully
comprehensive reference, but rather a guide for Principal
Investigators and Authorized Users.
Authority
The Laser Safety Manual is an enforceable component of the
Radioactive Material Broad Scope License and Radiation Producing
Devices Registrations under which the University of Houston is
authorized.
Training Requirements
All PIs and Authorized Users of Class 3b and 4 lasers
must attend and pass the laser safety training
Testing- requires at least 70% to pass. This test is used
to fulfill the requirement for users to demonstrate
competence.
Upon completion, be added to a sub-registration through
an amendment.
Online Annual Refresher Training. Testing requires at
least 80% to pass
Laser Safety Officer (LSO) duties
Ensure that users of lasers are trained in laser safety, as
applicable for the class and type of lasers the individual
uses.
Assume control and have authority to institute corrective
actions including shutdown of operations when necessary
in emergency situations or unsafe conditions.
Laser Light Shows CDRH Requirements
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LSO Duties Continued
Ensure maintenance and other practices required for the
safe operation of the lasers are performed.
Ensure the proper use of protective eyewear and other
safety measures.
Ensure compliance with the laser requirements and with
any engineering or operational controls specified by the
registrant.
Radiation Safety Responsibilities
Radiation Safety Committee - Technical Expertise,
Approve Facilities and Usage, Review Radiation Safety
Program, Support RSO Authority
Radiation Safety Officer and Staff - Radiation Safety
Manuals, Audits and Lab Reviews, Incident
Investigations, Health Physics Services, PI Consultations
and Technical Support
Principal Investigators – Compliance, AUs Safety and
Instruction
Authorized Users - Work Safely and follow the Rules
Administration Process
(mainly for PIs)
Laser Subregistration Application and Amendment
Location changes
Standard Operating Procedures
Change services
Laser purchasing, transfer, and disposal
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Radiation Safety Violations
Radiation Safety performs routine internal audits/inspections
These help assure compliance with the UH Laser Registration and
prevent a Notice of Violation (NOV) as a result of a state inspection
If a violation is found by a state inspector during the inspection, the
person committing the violation will be named on the NOV and not
the RSO
At UH, a Principal Investigator will be cited by Radiation Safety for
violations which include any aspect of their subregistration
conditions
Chronic violations of subregistration conditions can jeopardize a
Principal Investigator’s authorization to use lasers
Incident Notification
Individuals working with radiation must assume the
responsibility for their own safety and must ensure that
their actions do not result in a hazard to others.
In the event of a suspected or know exposure, immediately
stop work and notify your Principal Investigator and the
Radiation Safety Officer.
If it is determined that there is an acute localized exposure,
seek medical attention as soon as possible.
Emergency Information
EHLS office hours: Monday through Friday, 8:00 a.m. - 5:00 p.m.
For assistance with a radiation emergency or incident during
normal office hours call EHLS.
In the event of an after hours radiation emergency, contact the
UHDPS. EHLS maintains an on-call mechanism to provide
expertise in the event of an after hours situation requiring
assistance.
Radioactive material spills and emergency information is
available in the Radiation Safety Manual at
http://www.uh.edu/ehls
If you call after normal office hours about a non-emergency
incident, you may leave pertinent information on EHLS telephone
voicemail system.
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Emergency Telephone Numbers
EHLS – Main Line
RSO/CLSO - Otu
ARSO/CLSO - Sangho
Health Physicist - Darla
Health Center
DPS (Emergency)
DPS (Non-Emergency)
(713) 743-5858
(713) 743-5867
(713) 743-5870
(713) 743-5860
(713) 743-5151
911
(713) 743-3333
Exam
GOOD LUCK!
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