The visible light spectrum is the range of light wavelengths that are detectable by the human eye, spanning from approximately 400 nm to 700 nm and encompassing all the colors of the rainbow. Laser safety glasses are available in either clear or nearly clear lenses for lasers operating outside this spectrum.

However, for lasers operating within the visible light spectrum, some visible light must be blocked for safety, making it impossible for the lenses to be completely clear. The level of visible light transmission that is blocked by the lens is determined by the optical density, and the broader the coverage in the visible spectrum and the higher the optical density, the darker the lenses will be.

If your goal is to find laser safety glasses with the highest possible visible light transmission, you may want to consider glass filters as they generally have a higher VLT than plastic ones. The higher the VLT of your laser safety glasses, the easier it will be for you to see and work, but it’s important to note that some laser applications may require a specific VLT level for safety reasons according to OSHA. It is advisable to check with your Laser Safety Officer or the laser manual to determine if there are any VLT minimums for your laser or application.