Optical Density, commonly referred to as OD, is a measurement used to describe how effectively a laser safety filter attenuates laser radiation.

When viewing laser safety eyewear specifications, users may see ratings such as OD 3, OD 5, OD 7, or higher. These numbers indicate the reduction in laser energy transmitted through the lens at specific wavelengths.

Importantly, OD ratings are wavelength dependent. A lens may provide OD 7 protection at 1064nm but offer lower protection at other wavelengths. This is why reviewing the wavelength protection chart is critical when selecting laser safety glasses.

Manufacturers test filters across defined wavelength ranges and publish the results to help users determine compatibility with their laser systems.

Understanding optical density allows users to better interpret laser safety specifications and make informed decisions when selecting protective eyewear.