Each laser operates at a specific wavelength, and protective eyewear must be designed to attenuate that particular range. Because of this, a single pair of laser safety glasses cannot always protect against every laser type.

Filters inside the lenses are engineered to block certain wavelengths while allowing visible light to pass through for practical vision. If the wavelength of the laser falls outside the rated protection range, the eyewear may not provide effective attenuation.

For example, eyewear designed for visible lasers may not provide sufficient protection against infrared wavelengths. This is why lens markings list both wavelength ranges and optical density ratings.

In facilities where multiple lasers are used, operators may need different eyewear depending on the equipment being operated.

Matching the eyewear to the laser wavelength is one of the most important aspects of laser safety.