What does optical density measure in laser eyewear?

Optical density measures the attenuation of radiant laser energy, which indicates how much laser light can be absorbed or transmitted by a material. In the context of laser eyewear, optical density is crucial because it helps determine the level of protection the eyewear provides against harmful laser wavelengths. A higher optical density means that the eyewear will allow less laser light to pass through to the eyes, thereby increasing safety for the wearer.

This property is particularly important in environments where lasers are used, as it ensures that individuals are adequately protected from the potential harmful effects of intense light exposure. The other options do not directly pertain to the primary function of laser eyewear, which is to protect eyes from high-energy light, making the understanding of optical density pivotal in selecting the appropriate eyewear for specific laser applications.