|Transmission||10%, 20% or custom||Aperture BBAR Coating on back surface S2||Optional|
|Dimension Tolerance||±0.2mm||Clear Aperture||+/-0.2mm90% of outside dimension|
|Surface Quality||80/50 S/D||Flatness||2-4 waves per 25mm|
|Parallelism||3-5 arc minutes||Mechanical||Unmounted|
Metallic-coated infrared neutral density filters (IR ND filters) 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.
Infrared Neutral Density Filters are designed to attenuate radiation over a wide spectral range. These filters are coated on germanium substrates. The ND coating is optimized at 2.2 microns and can be used out to 15 microns.
1. Transmission of IR ND filters (Germanium, T=10%, BBAR coating on back surface S2)
2. Transmission of IR ND filters (Germanium, T=10%, No BBAR coating on back surface S2)