What must all laser eyewear have labeled on them?

All laser eyewear must have the wavelength ranges of protection and optical density (O.D) labeled on them because this information is crucial for ensuring the safety of individuals working with lasers. The wavelength range indicates which specific wavelengths of laser light the eyewear can effectively block, allowing users to know whether they are adequately protected from the laser radiation they may encounter. The optical density value provides a measure of how much laser light is attenuated by the eyewear, indicating its effectiveness at reducing the intensity of the laser to safe levels.

This labeling allows users to make informed decisions when selecting appropriate eyewear based on the specific types of lasers they will be working with, thereby minimizing the risk of eye injury. This requirement is essential in maintaining safety standards in environments where lasers are used.