Appropriate laser protective eyewear must be used for beam alignments or anytime an open beam exceeds if the viewed beam exceeds the ANSI Z136.1 MPE (maximum permissible exposure) value. All eyewear must be labeled with the optical density and wavelength.
Laser protective eyewear is usually not required for Class 2 or 3R laser or laser systems unless viewed by certain optical aids.
Factors in selecting eyewear:
- Laser power and/or pulse energy
- Wavelength(s) of power output
- Potential for multi-wavelength operations
- Radiant exposure or irradiance levels for which protection (worst case) is required
- Exposure time criteria
- Maximum permissible exposure (MPE)
- Optical Density requirement of eyewear filters at laser output wavelengths
- Angular dependence of protection afforded
- Visible light transmission requirement and assessment of the effect of the eyewear on the ability to perform the task while wearing the eyewear
- Need for side-shield protection and maximum peripheral vision requirement; side shields shall be considered and should be incorporated where appropriate
- Radiant exposure or irradiance and the corresponding time factors at which laser safety filter characteristics change occurs, including transient bleaching especially for ultra-short pulse lengths
- Need for prescription glasses
- Comfort and fit
- Degradation of filter media, such as photo-bleaching
- Strength of materials (resistance to mechanical trauma and shock)
- The capability of the front surface to produce a hazardous specular reflection
- The requirement for anti-fogging design and coatings
Laser protective eyewear should be inspected before each use for damage, and or cleanliness, and replaced if necessary. Contact the LSO for assistance in selecting eyewear at lso@berkeley.edu.