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SECTION
E3: LASER SAFETY
Introduction
The term LASER is an acronym that stands for Light Amplification
by Stimulated Emission of Radiation. The light which the laser produces
is unique in that it is monochromatic, directional and coherent. Lasers
are primarily used in research laboratories, but have been incorporated
in other devices, including classroom pointers, level indicators used
during construction, and land survey instruments.
Most lasers used at Princeton University are capable of causing eye
injury to anyone who looks directly into the beam or its reflections
from a specular (mirror-like) surface. In addition, diffuse reflections
of a high-power laser beam can produce permanent eye damage. High-power
laser beams can burn exposed skin, ignite flammable materials, and heat
materials that release hazardous fumes, gases, debris, or radiation.
Equipment and optical apparatus required to produce and control laser
energy may also introduce additional hazards associated with high voltage,
high pressure, cryogenics, noise, other forms of radiation, flammable
materials, and toxic fluids. Thus, each proposed experiment or operation
involving a laser must be evaluated to determine the hazards involved
and the appropriate safety measures and controls required.
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Scope and Application
The Radiation Safety Committee
(RSC) is responsible for establishing a University laser safety
program. The RSC recently established a Laser Safety Subcommittee to
consider and recommend a laser safety policy and program. In the meantime,
the Office of Environmental Health and Safety (EHS) strongly recommends
that individuals using lasers set up and operate laser facilities to
meet the laser safety guidelines established by the American
National Standards Institute (ANSI) standard ANSI Z136.1-1993, American
National Standard for the Safe Use of Lasers.
The Laser Safety Program applies to individuals who operate or work
in proximity to Class 2, Class 3 or Class 4 lasers, as described below.
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Program Description
Laser Classification
The ANSI has established guidelines for use of lasers in standard ANSI
Z136.1-1993. This standard classifies lasers into four main classes
and establishes safe work practices for each hazard class.
- Class 1 lasers are low-power
lasers which do not normally pose a hazard.
- Class 2 lasers are low-power
visible lasers or laser systems that cannot cause eye damage unless
they are viewed directly for an extended period of time.
- Class 3 lasers are medium-power
lasers and laser systems capable of causing eye damage with short
duration exposures to the direct or specularly reflected beam. They
are subdivided into two subclasses.
- Class 3a lasers normally do
not present a hazard if viewed momentarily with an unaided eye,
but may present a hazard if viewed using collecting optics.
- Class 3b lasers can present
a hazard if viewed directly. This includes intrabeam viewing of
specular reflections.
- Class 4 denotes high-power lasers
and laser systems that may cause severe eye injury with short duration
exposure to the direct or reflected beam. They may also cause severe
skin damage and present a fire hazard.
Commercial lasers are classified by the manufacturer. When a commercial
laser is modified or when a new laser is constructed in the laboratory,
it is the responsibility of the Principal Investigator to classify and
label the laser per the ANSI standard. EHS can assist in determining
the appropriate classification.
Laser Inventory
EHS keeps an inventory of all Class 3 and Class 4 lasers and reviews
and approves purchases of these lasers. The Purchasing
Office notifies EHS of any purchase requisitions involving lasers,
laser systems, and accessories. EHS reviews this information and approves
the purchase. This helps to ensure that laboratories using high powered
lasers are evaluated for safety controls before the laser is put into
service.
Training
Individuals who work with or in close proximity to Class 2, Class 3,
or Class 4 lasers must attend laser safety training provided by EHS.
This training includes:
- fundamentals of laser operation
- biological effects of laser radiation on the eye and skin
- non-radiation hazards (e.g., fire hazards, chemical exposure)
- classification of lasers and laser systems
- control measures and personal protective equipment
Individuals who work with or in close proximity to Class 3b or Class
4 lasers receive additional training from EHS, including:
- relations of specular and diffuse reflections
- maximum personal exposure levels for eye and skin under all conditions
- laser hazard evaluations and range equations
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Roles and Responsibilities
Department
- Identify laser products that are covered by the ANSI Standard and
establish procedures to ensure that the recommendations of the Standard
are followed.
- Ensure individual who work with or around lasers have received
the proper laser safety training.
- Establish a safety review procedure to determine that adequate
hazard analyses and corrective actions have been completed for all
applicable laser systems.
Supervisors
- Be knowledgeable of the education and training requirements for
laser safety, the potential laser hazards and associated control measures
for all lasers under their control.
- Report known or suspected accidents to EHS.
- Ensure that lasers under their control are not operated or modified
without approval of the supervisor or principal investigator.
- Ensure that all administrative and engineering controls are followed.
- Maintain inventory control and a permanent record of the status
of all Class 3b, and Class 4 lasers
- Provide an annual inventory of Class 3b and Class 4 lasers to EHS.
- Ensure that individuals working with lasers have attended the
general laser safety training and provide laser operators with training
in
the administrative, alignment and standard operating procedures.
- Classify and label any unclassified lasers.
- Attend University's laser safety training programs.
- Ensure that laser workers are registered for the medical surveillance
program.
- Notify EHS immediately in the event of an exposure to a Class 3
or Class 4 laser.
- Provide standard operating procedures (SOP), in accordance with
ANSI Z136.1-1993 and any established University policy, for all laser
operations involving Class 3 and Class 4 lasers detailing alignment,
operation and maintenance procedures.
Purchasing Office
- Notify EHS when orders for Class 3 and Class 4 lasers are placed
EHS
- Review and approve the purchase of Class 3 and Class 4 lasers
- Provide assistance in evaluating and controlling hazards.
- Maintain records of lasers and laser operators.
- Conduct laser safety training.
- Participate in accident investigations involving lasers.
- Periodically audit the departmental Laser Safety Program.
Individual
- Attend laser safety training
- Be familiar with specific safety hazards of lasers which is being
operated or working near.
- Follow standard operating procedures and comply with requirements
established by the Laser Safety Committee, Laser Safety Officer and
the supervisor.
- Use Class 3b or Class 4 lasers only if specifically authorized
by the laser supervisor.
- Report known or suspected accidents to the supervisor and EHS.
- Inform spectators about and protect spectators from all potential
laser hazards
- Register for the medical surveillance program
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For More Information
Contact the Laser Safety Officer
at 258-6271 for more information.
See the Princeton University Laser
Safety Training Guide.
A Laser Safety Self-Audit Checklist is available through EHS or may
be downloaded either as a PDF
or a customizable Word document.
The following resources and training aids are available through EHS:
- ANSI Standard Z136.1-2000, American National Standard for the
Safe Use of Lasers, 2000
- CFR Chapter I, Subpart J, Part 1040 - Performance Standard for
Light Emitting Products (the Food and Drug Administration requirement
document for light emitting products.
- Videocassette: High Powered Lasers in the Lab, Interactive Medical
Communications, 1994
- Goldman, Leon, Application of the Laser, CRC Press, 1977
- Pressley, Robert J., Ph.D., editor, CRC Handbook of Lasers, CRC
Press, 1971
- Seigman, Anthony E., Lasers, University Science Books, 1986
- Mallow, Alex and Leon Chabot, Laser Safety Handbook, Van Nostrand
Reinhold, 1978
- Slirey, David, Safety with Lazers and Other Optical Sources, a
comprehensive handbook, Plenum Press, 1980
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