Class | Relative Power | Detail Spec | Typical Source | Safety Note |
I | Low | - Not capable of producing damaging radiation levels during operation or maintenance.
- Class I lasers are sealed in an enclosure that prohibits or limits access to the laser radiation (i.e., a laser printer). Beam power is less than 0.4 uW for visible CW lasers.
- Exempt from control measures
| | Safe - when operated normally |
II | Low - visible | - All Class II lasers operate within the visible region of the spectrum (400-700 nm)
- Output is not intended to be viewed (for example, a grocery scanner)
- Eye protection is normally afforded by the aversion response to bright light (blink)
- Upper power limit for Class II continuous wave (CW) lasers is 1 mW
- Class II lasers shall have a “Caution” sign posted on the outside door
| - Laser diodes
- Ultrabright LEDs
| Caution - do not view directly without eye protection |
IIIa | Medium | - Power output is up to 5 times greater than Class II - 5m W
- Laser or laser systems that would not normally produce a hazard if viewed for only a moment with the unaided eye (for example a laser pointing device)
- Beams may present a hazard if viewed through collecting optics
- Class lIIa lasers shall have a “Caution” sign posted on the outside of the door
| - High power laser diodes
- Optical amplifiers
- Pmp lasers
| Danger - eye protection required |
IIIb | Medium | - Maximum power output is less than 500 mW
- CW lasers operate between the upper Class IIIa limits (5mW) and the maximum power for Class IIIb lasers (500 mW)
- Diffuse reflections are usually not hazardous. However, lasers or laser systems may produce a hazard if viewed directly through intrabeam viewing or specular reflections
- Class IIIb lasers shall have a “Danger” sign posted on the outside of the door
| - High power laser diodes
- Optical amplifiers
- Pump lasers
| Danger - eye protection required |
IV | High | - Power exceeds Class IIIb limits of 500mW
- High-powered lasers and laser systems capable of causing severe eye damage with short duration exposures (0.25 seconds) to the direct, specularly, or diffusely reflected beam
- Capable of causing severe skin damage
- Can ignite flammable and combustible materials
- May produce laser generated air contaminants or hazardous plasma radiation
- Class IV lasers shall have a “Danger” sign posted on the outside of the door
| - Medical lasers
- Industrial lasers
| Extreme danger - eye protection and physical protection required |
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