US 6,444,984 B1 · Solid cryogenic optical filter

Abstract

An optical filter system is described wherein a fluid, such as gaseous phases of water or carbon dioxide, is frozen onto a transmissive substrate positioned in the optical path of an infrared sensor system. The frozen material, which is preferably maintained at cryogenic temperatures, acts as a natural optical filter, absorbing certain undesirable wavelength bands of atmospheric infrared radiation, thus preventing them from reaching the detector of the sensor system. Simultaneously, the optical filter system allows certain desirable wavelength bands of infrared radiation to be transmitted, thus permitting them to reach the detector of the sensor system. The overall effect is to reduce the amount of noise and clutter generated by the undesirable atmospheric infrared radiation from reaching the detector of the sensor system, thus increasing the resolution and effectiveness of the sensor system.

Claims42

Dependent claims

An optical filter, comprising:

a substrate transmissive to infrared radiation, wherein the infrared radiation includes at least two different wavelength bands;
and
an erasable layer of material formed on at least a portion of a surface of the transmissive substrate, wherein the material substantially absorbs at least one of the at least two different wavelength bands of the infrared radiation so as to substantially prevent the transmission of one of the at least two different wavelength bands of the infrared radiation through the transmissive substrate.

Dependencies are inferred from the claim text.

Solid cryogenic optical filter

Life of this patent

Solid cryogenic optical filter

Life of this patent

Abstract

Claims42