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Classes of Lasers

The American National Standards Institute (ANSI) has established a laser hazard classification system in publication ANSI Z136.1-2000, Safe Use of Lasers. Certified laser manufactures are required to label their products as to the Class type as of September 19, 1985 (21 CFR Part 1040). Information regarding appropriate eyewear for a specific laser may be obtained from the manufacturer at time of purchase. The following table summarizes this laser classification scheme and the hazard capabilities associated with each class of laser.

Class of
Laser

Hazards

1

Eye safe lasers; may not produce hazardous radiation

2

Continuous intrabeam viewing can cause eye damage; momentary intrabeam exposure (< 0.25 sec) is not damaging to the eye; visible radiation only

2a

Continuous intrabeam viewing can cause eye damage; the accessible radiation shall not exceed Class 1 accessible emission limit (AEL) for an exposure duration of 1000 seconds

3a

Invisible lasers having an output power < 5x the Class 1 AEL or visible laser having an output power < 5 mW; capable of causing damage through intrabeam viewing, with optical instruments or through viewing a specular reflection for < 0.25 sec

3b

Invisible lasers having output power <500 mW; as with 3a lasers, 3b lasers can cause injury through intrabeam viewing, viewing with optical instruments, or through viewing a specular reflection

4

Beam power > 500 mW; intrabeam exposure, exposure to specular- and diffuse reflections capable of causing eye- and skin damage; fire hazard due o their power density