How to Choose Your Laser Safety Glasses
Laser standards and categories
1, ANSI Z136.1 requires specification of laser safety eyewear according to optical densities (OD). OD is the logarithmic reciprocal of transmittance, expressed by the following: D? = -log10 T ?, where T is transmittance.
2, European laser safety regulations EN 207/EN208 consider Optical Density and also the damage threshold when determining laser safety requirements.
Lasers are categorized by the ANSI Z136.1 standard and IEC CE EN207/EN208 standard into the following general categories.
According to the American laser safety standard ANSI Z136.1 and the International Electrotechnical Commission and the European Union laser safety standard IEC CE EN207/EN208, lasers can be classified according to the following standards.
|
Class |
Definition |
Suggestion |
|
1 |
Non-hazardous | Eyewear not required. |
|
1M |
Eye safe visible laser (400-700nm) if used without magnifying optics. |
Eyewear not required. |
|
2 |
Eye safe visible laser (400-700nm) (safe within the blink reflex of 0.25s). | Eyewear not required. |
|
2M |
Eye safe visible laser (400-700nm) (safe within the blink reflex of 0.25s) if used without magnifying optics. |
Eyewear recommended. |
|
3R |
Likely unsafe for intrabeam viewing. Maximum Permissible Exposure (MPE) is up to 5 times class 2 limit for visible lasers of 5 times class 1 limit for invisible lasers. |
Eyewear recommended. |
|
3B |
Eye hazardous for intrabeam viewing. Limited diffuse hazard. |
Eyewear recommended. |
|
4 |
Eye and skin hazard for direct and diffuse exposure. Fire and burn hazard. |
Eye protection and other personal safety equipment is required. |
|
Optical Density |
Transmission% |
Attenuation Factor |
|
0 |
1 |
1 |
|
1 |
0.1 |
10 |
|
2 |
0.01 |
100 |
|
3 |
0.001 |
1000 |
|
4 |
0.0001 |
10000 |
|
5 |
0.00001 |
100000 |
|
6 |
0.000001 |
1000000 |
|
7 |
0.0000001 |
10000000 |
Selection
1, Laser’s specifications: output wavelength, power density
2, Optical Density（OD）： Optical Density (OD) is a measure of the attenuation of energy passing through a filter. The higher the OD value, the higher the attenuation
3, Visible Light Transmittance（VLT): VLT below 20% should be used in well-illuminated working environments.
4, Frame: wear or do not wear prescription glasses, face-forming
