What the standard defines
How laser protective eyewear is tested and marked: the wavelength ranges it protects against, the protection level at each range, and the mode of laser operation the rating applies to. The marking on the frame or lens is the product’s declaration under that framework, and it is the only statement of protection a buyer can compare.
Optical density itself is a physical measure: the base-ten logarithm of how much a filter attenuates light at a given wavelength. A lens can be dense at one wavelength and nearly transparent at another.
What it does not promise
No protection outside the marked wavelengths. A lens rated for the blue light of many diode lasers may offer nothing against the far infrared of a CO2 tube. No suitability judgement for a specific laser: the laser maker’s instructions state what protection its product requires. No evidence from colour: a tinted lens without a marking gives no information about its filter. No comfort or fit guarantee, which depends on the frame, side shields and prescription glasses underneath.
What it works with
The laser class and wavelength published by the laser maker, which decide what the eyewear must cover. On a glasses page, this site reports the wavelength range, optical density, marking, fit, side protection and visible light transmission as published, and never calls a pair safe for a given laser.
Questions makers ask before buying
What does one step of optical density mean?
The scale is logarithmic: each whole step reduces the transmitted light at that wavelength by a factor of ten. The density a laser requires is set by its power and the laser maker’s instructions.
Can one pair cover a diode and a CO2 laser?
Only if its marking names both wavelength ranges. The two lasers emit very different wavelengths, and a filter made for one may do little for the other.
Last reviewed 15 September 2026