Circular Variable Neutral Density Filters change the intensity of light from 100% to less than 0.1%. As the filter rotates, beam intensity changes due to variations in the metallic coating around the filter. These filters change optical density, transmission, substrate, coating, and size to match applications. Filters come in linear optical density, transmission, and customized densities. Filter substrates include BK-7, fused silica, ZnSe, and Ge, among others. Typical coating is a nickel variant for room temperature, low-power applications. But the ND coating can be enhanced for hostile environments.
Reynard Corp., 1020 Calle Sombra, San Clement, CA 92673, (949) 366-8866, reynardcorp.com