LASER SAFETY

A production of Environmental Health and Safety

LEHIGH UNIVERSITY

Introduction

There are a wide variety of lasers used in research andclassroom instruction at Lehigh University. This safety

presentation provides basic instructional direction to

help personnel use lasers safely.

Laser safety requirements are established under ANSI(American National Standard Institute) standard Z136.5

and are required by the Occupational Safety and Health

Administration (OSHA).

Standard Operating

ProceduresFaculty and staff are to develop standard operatingprocedures outlining safety guidelines to follow when

laser equipment is used in their laboratory(s). All

personnel should read and sign the SOP and follow the

guidelines whenever using the laser(s).

Laser Classifications

Class I - Exempt Lasers - cannot emit radiation at know

hazard levels. Range 0.4 uW at visible

wavelengths.

Class II - Low Power Visible Lasers – Emit a radiant power greater

than Class I but less than 1mW.

Class II A - Low Power Visible Lasers – The upper power limit is

4.0 uW.

Class III A - Medium Power Lasers – 1-5mW

Class IIIB - Medium Power Lasers – 5-500 mW, pulsed: 10

J/cm2

Class IV - Greater than 500mW, pulsed greater than 10 J/cm2

Laser Safety Officer

The Laser Safety Officer (LSO) is a faculty member or fulltime staff member who has primary responsibility for laser

safety in their laboratory. The LSO is responsible for:

• Control Measures • Hazard Identification

• Procedure Approval • Personal Protective

Equipment

• Signs and Labels • Approval of Equipment and

Facility

• Training • Medical Surveillance

Research Student / Laser

Worker

Research students and laser workers must be trained inlaser safety prior to using laser equipment. Research

students and laser workers also have the responsibility to:

• Get a medical eye exam prior to operating Class

IIIb and Class IV laser equipment.

• Follow laboratory standard operating procedures.

• Wear appropriate personal protective equipment.

• Report defective equipment and any injuries to theLSO.

Laboratory Protection

Measures

Protective Barrier

or Walls to Room

Beam Trap or

Beam Stop

Controlled Access

Key Control Laser Warning SignCovered Window

Overhead View of Laser Table

Laser

Fire Extinguisher

Attenuator

Nominal Hazard Zone

Laboratory Protection

Measures

When the laboratory has multiple uses, laser barriers areused to protect other workers from being exposed to a

stray laser beam. If the laboratory has one worker or one

laser set up, or the operation is a closed system (beam is

not exposed), the partitions may not be required.

Protective Housing

The ASNI standard requires that an enclosure be placedaround the laser under normal operation for all classes of

lasers. The housing may be removed for alignment and

maintenance procedures. The laser warning label which

identifies the class of the laser must also be visibly

present.

Key Switch Control

All Class IIIb and Class IV lasers require a masterswitch control which is operated by either a key or

computer access.

Attenuator

An attenuator is a filter that can reduce the outputemission to a level at or below the maximum permissive

exposure (MPE) level when the laser is on. The

attenuator is useful when aligning the beam, allowing the

user to safely align the beam while reducing the risk of

injury.

Controlling Laser

Beams

Beam traps are used at the endof a laser display to absorb the

energy created by the laser

beam.

Beam stops are useful whencontrolling higher powered

lasers and larger areas to

prevent accidental beam stray.

Beam Trap

Beam Stop

This beam

absorber has an

inverse cone-

shaped graphite

core which is

embedded in an

aluminum holder.

Three radiative

fins are included

for efficient heat

dissipation.

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Service Access Panels

Service access panels are required by the ANSIstandard on all lasers. The panel is only to be removed

by service personnel. The panel must be equipped with

an interlock on class III b or class IV laser and a sticker

identifying the laser as to its classification.

Interlocks

Interlocks are safety switchesthat are designed to immediately

power down the laser prior to

accidental exposure to the laser

beam or electrical hazards.

Interlocks can be found both

inside the laser (to prevent

access to electronic components

during operation) and outside

the laser (to preventunauthorized access to the

laboratory during laser

operation).

Laser Activation Warning

SystemWarning devices shouldbe used with class III b

and shall be used with

class IV laser

laboratories.

The warning device

may produce a sound

or a light such as the

one shown in this

photograph.

These systems are to

be activated upon

powering the laser

system.

Controlled Access

Areas

The areas in which Class III B and Class IV lasers areused must be restricted. Unnecessary spectators must

be limited and all personnel within the restricted area

must be protected from unexpected exposure to laser

beams.

• Keep doors closed (and if possible locked)

when using the laser.

• Activate the laser “in use” light.

• Deactivate laser if someone wishes to enter.

Laser Warning

SignsLaser warning signs are required for Class III A, Class IIIB and Class IV lasers. The colors are red, black and

white and the word DANGER appears at the top with a

laser burst symbol. The laser type and output are also

listed. Authorized Personnel Only or Eye Protection

Required may also be added to the sign.

Eye Protection

Multi-lensGoggles

SingleWavelength

Glasses

AcrylicWindows

Eye protection is required in laser laboratories whether itis worn by the individual or placed within a viewing port.

Basic Laser Safety Rules

1. Doors should be closedwhen lasers are in use.

Any opening such as a

window should be covered.

2. Access should be restrictedand the “in use” light should

be illuminated.

3. Wear long sleeve shirts and

remove jewelry such as

watches, necklaces, andrings.

Basic Laser Laboratory Safety

Rules4. Make sure you read and follow the

laboratory SOP (Standard Operating

Procedure) and the laser operating

guide.

5. Follow the beam alignment

procedures carefully. Ensure the

beam is located below eye level and

if possible use the attenuator.

Otherwise, make sure the beam is

below the maximum permissible

exposure (MPE).

6. Appropriate eye protection should be

used.

Other Laboratory Hazards

There are other hazards that may be found in a laserlaboratory. Often researchers working with lasers are

exposed to live electrical components and water which is

used for cooling. This presents a potential for fire or

electrocution. Compressed

gases are also common inlaser laboratories. Personnel

should receive safety training

for electrical safety,

compressed gases, andhazardous materials.

Emergency Response

If a fire develops in your laboratory, sound the alarmand exit the building. Only use an extinguisher if the fire

is in the beginning stages and you are trained in fire

extinguisher use. Wait for the police and firemen so you

can explain what the problem is and where it is located.

If you receive a shock, are burned, become blinded or

become exposed to hazardous materials, call

University Police at 84200. They will direct theemergency response personnel to your location.

Further Information

For further information on laser safety, refer to the LaserSafety Guidelines published by Environmental Health and

Safety. A copy is available to you simply by calling 84251.

To speak to someone regarding laser

safety, contact Occupational SafetyManager Randy Shebby at 86240.

Further safety information may be obtained at the OSHA

web site www.osha.gov or referring to ANSI standard

Z136.5-2000 Safe Use of Lasers in EducationalInstitutions.