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Oregon State University

Control Measures by Laser Classification

Potential hazards exist to all individuals working near a laser system.  Such individuals should be warned of the existence and location of lasers, and of the meaning of the warning labels for all classes of lasers. 

Particular attention should be given to the environment where the laser is used.  This factor should be considered together with the class and application of the laser for determining the control measures to be applied.  Basic elements to be considered are:

  •  number and class of lasers
  •  laser location
  •  presence (access) of uninformed, unprotected personnel
  •  permanence of beam paths
  •  presence of objects that may have specular surfaces or reflecting objects near the beam path
  •  use of optical devices such as lenses, microscopes, etc.

Control measures may be broken down to two types: administrative controls, such as training, signage, procedures, etc., and engineering controls, such as key controls, interlocks, beam housings, shutters, etc. Engineering controls are design features or devices applied to a laser system and are considered the most effective of the two types of controls.

The following are general considerations for work with lasers, per laser hazard class. The table below provides a summary of these control measures.

Class 1

Many Class 1 lasers have higher class lasers enclosed within a protective housing.  If the Class 1 laser has an enclosed Class 3b or 4 laser, interlocks should be provided on any removable parts of the housing, or the laser should have a service access panel that is either interlocked or requires a tool for removal.  If the protective housing is removed, control measures appropriate for the enclosed laser class should be followed. 

All Class 1 lasers must be labeled.

 

Class 2

Class 2 lasers must be labeled. 

The laser beam should not be purposefully directed toward the eye of any person.  Alignment of the laser optical systems (mirrors, lenses, beam deflectors, etc.) should be performed in such a manner that the primary beam, or specular reflection of the primary beam, does not expose the eye to a level above the MPE for direct irradiation of the eye.

The work area should be posted with a warning label or sign cautioning users to avoid staring into the beam or directing the beam toward the eye of individuals.

If the MPE is exceeded, design viewing portals and/or display screens to reduce exposure to acceptable levels.

If the Class 2 laser has an enclosed Class 3b or 4 laser, interlocks should be provided on any removable parts of the housing, or the laser should have a service access panel that is either interlocked or requires a tool for removal.  If the protective housing is removed, control measures appropriate for the enclosed laser class should be followed. 

 

Class 3a (3R)

Class 3a lasers must be labeled accordingly.  The work area should be posted with a warning label or sign cautioning users to avoid staring into the beam or directing the beam toward the eye of individuals.

Removable parts of the housing and service access panels should have interlocks to prevent accidental exposure.  A permanent beam stop or attenuator may also be used.

If the MPE is exceeded, design viewing portals and/or display screens to reduce exposure to acceptable levels.  Alignment procedures should be designed to ensure the MPE is not exceeded.

 

Class 3b

Class 3b lasers and laser systems must be labeled accordingly.  These lasers are used in areas where entry by unauthorized individuals can be controlled.  If an individual who has not been trained in laser safety must enter the area, the laser operator or supervisor should first instruct the individual as to safety requirements and must provide protective eyewear, if required.

If the entire beam is not enclosed or if a limited open beam exists, the laser operator, supervisor or laser safety officer should determine a Nominal Hazard Zone (NHZ).  An alarm, warning light or verbal countdown should be used during use or start up of the laser.

The controlled area should

·       have limited access to spectators,

·       have beam stops to terminate potentially dangerous laser beams,

·       be designed to reduce diffuse and specular reflections,

·       have eye protection for all personnel,

·       not have a laser beam at eye level,

·       have restrictions on windows and doorways to reduce exposure to levels below the MPE, and

·       require storage or disabling of the laser when it is not being used.

If the MPE is exceeded, design viewing portals and/or display screens to reduce exposure to acceptable levels.  Alignment procedures and collecting optics should be designed to ensure the MPE is not exceeded.

Only authorized, trained individuals should service the laser.  Approved, written standard operating, maintenance and service procedures should be developed and followed.

 

Class 4

In addition to the control measures described for Class 3b, Class 4 lasers should be operated by trained individuals in areas dedicated to their use.  Failsafe interlocks should be used to prevent unexpected entry into the controlled area, and access should be limited by the laser operator to persons who have been instructed as to the safety procedures and who are wearing proper laser protection eyewear when the laser is capable of emission.

Laser operators are responsible for providing information and safety protection to untrained personnel who may enter the laser controlled areas as visitors.

The laser area should be

  •  restricted to authorized personnel only
  •  designed to allow for rapid emergency egress
  •  equipped with a device that allows for deactivation of the laser or reduction of the output to below the MPE
  •  designed to fulfill Class 3b controlled area requirements
  •  designed with entry safe controls
  •  designed such that the laser may be monitored and fired from a remote location
  •  (for pulsed systems) have interlocks designed to prevent firing of the laser by dumping the stored energy into a dummy load
  •  (for continuous wave systems) have interlocks designed to turn off the power supply or interrupt the beam by means of shutters.

The beam path must be free of specularly reflective surfaces and combustible objects and the beam terminated in a non-combustible, non-reflective barrier or beam stop.

 

Control Measures for the Four Laser Classes

Control Measures

Classification

Engineering Controls 

1 

1M

2 

2M

3R 

3B 

4 

Protective Housing

X

X

X

X

X

X

X

Without protective housing

Laser Safety Officer establishes alternative controls

Interlocks on protective housing

à 

à

à 

à 

à 

X

X

Service Access Panel

à 

à

à 

à 

à 

X

X

Key Control

--

--

--

--

--

· 

X

Viewing Portals

Assure viewing limited < MPE

Collecting Optics

             

Totally Open Beam Path

--

--

--

--

--

X
NHZ

X
NHZ

Limited Open Beam Path

--

--

--

--

--

X
NHZ

X
NHZ

Enclosed Beam Path

None required if protective housing and interlocks in place

Remote Interlock Connector

--

--

--

--

--

· 

X

Beam Stop or Attenuator

--

--

--

--

--

· 

X

Activation Warning Systems

--

--

--

--

--

· 

X

Indoor Laser Controlled Area

--

--

--

--

--

--

X

Class 3B Indoor Laser Controlled Area
--
--
--
--
--
X
--
Class 4 Laser Controlled Area
--
--
--
--
--
--
--
Outdoor Control Measures
--
--
--
--
--
--
--
Laser in Navigable Airspace

X

·
NHZ

X
NHZ

·
NHZ

X
NHZ

X
MPE

X
MPE

Temporary Laser Controlled Area

à
MPE

à
MPE

à
MPE

à
MPE

à
MPE

--

--

Controled Operation

--

--

--

--

--

--

· 

Equipment Labels

X

X

X

X

X

X

X

Laser Area Warning Signs

--

--

--

X

·

X

X


Administrative and Procedural Controls 

Standard Operating Procedure

--

--

--

--

--

· 

X

Output Emission Limitations

--

--

--

--

--

LSO Determines

Education and Training

--

· 

· 

· 

· 

X

X

Authorized Personnel

--

*

--

*

--

X 

X

Alignment Procedures

à

à

à

à

à

X

X

Protective Equipment

--

*

--

*

--

·

X

Spectator

--

*

--

*

--

·

X

Service Personnel

à

à

à

à

à

X

X

Demonstration with Public

--

*

X

*

X

X

X

Laser Fiber Optic Systems

MPE

MPE

MPE

MPE

MPE

X

X

Laser Robotic Installation

--

--

--

--

--

X
NHZ

X
NHZ

Protective Eyewear

--

--

--

--

--

·
MPE

X
MPE

Window Protection

--

--

--

--

--

X

X
NHZ

Protective Barriers and Curtains

--

--

--

--

--

· 

· 

Skin Protection

--

--

--

--

--

X

X
MPE

Warning Signs and Labels

--

--

·

·

·

X
NHZ

X
NHZ

Skin Protection

--

 

--

--

--

X
MPE

X
MPE

LEGEND 

X = shall       · = should      -- = no requirement    NHZ = NHZ analysis required

à = shall if enclosed Class 3b or 4            MPE = shall if MPE is exceeded

                 

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