Patent ID: 7816650

Claim:
An external optical relay assembly to match a fore optic having a first f-number and a first aperture stop to an infrared camera having a cold stop, comprising a second f-number and a second aperture stop, wherein said first f-number comprises f-numbers that are the same as and different than said second f-number, said external optical relay assembly comprising: optical components; wherein said optical components disposed within said external optical relay assembly cause an image of said first aperture stop to be formed within said external optical relay assembly; and wherein said optical components disposed within said external optical relay assembly further cause said image of said first aperture stop to be formed at substantially a same plane as said second aperture stop; and a third aperture stop disposed within said optical components; wherein said third aperture stop disposed within said external optical relay assembly at substantially a same plane as said image of said first aperture stop; wherein said third aperture stop being thermally cooled; wherein said third aperture stop substantially centered along an optical axis; and wherein said third aperture stop causes said first f-number to effectively match said second f-number and said optical components cause an image of an object of said fore optic to be formed on substantially a same plane as a focal plane of said infrared camera.