The Spectral Systems Infrared Neutral Density Filters are metallic-coated neutral density (ND) filters which obtain their optical density from a metal alloy coating on a substrate determined by the wavelength region of interest. Unlike the all-dielectric or absorption type, the metallic type ND filter employs a combination of absorption and reflection to reduce the intensity of light. Unlike screen type devices, our ND filters provide a consistent light intensity over the full beam area. Neutral Density Filters are often used to reduce the intensity of the infrared (IR) beam for highly sensitive detectors preserving linearity and improving photometric accuracy. ND Filters are also ideal for evaluating the performance of optical systems and components within a controlled experiment. ND Filters are designed to reduce transmission evenly across a portion of the spectrum by absorbing or reflecting the portion of the light that is not being transmitted. Please contact us for other requirements.