US 12,292,547 B2
Athermal infrared optical telescope and method for manufacturing
David N. Sitter, Jr., Torrance, CA (US)
Assigned to Raytheon Company, Arlington, VA (US)
Filed by Raytheon Company, Waltham, MA (US)
Filed on Mar. 19, 2021, as Appl. No. 17/207,350.
Prior Publication US 2022/0299679 A1, Sep. 22, 2022
Int. Cl. G02B 1/02 (2006.01); G02B 13/14 (2006.01); G02B 13/18 (2006.01); G02B 23/16 (2006.01); G02B 25/00 (2006.01); H04N 23/50 (2023.01); H04N 23/57 (2023.01)
CPC G02B 1/02 (2013.01) [G02B 13/14 (2013.01); G02B 13/18 (2013.01); G02B 23/16 (2013.01); G02B 25/001 (2013.01); H04N 23/50 (2023.01); H04N 23/57 (2023.01)] 20 Claims
OG exemplary drawing
 
1. A device comprising:
an entrance pupil configured to receive light from a distant source;
an exit pupil configured to output the light to at least one component of an imaging system;
a plurality of lenses disposed optically between the entrance pupil and the exit pupil, the lenses grouped into an objective group and an eyepiece group; and
a housing surrounding the lenses and formed of a housing material;
wherein the lenses of the objective group and the eyepiece group are formed of one or more lens materials selected to have a focal thermo-optical coefficient that is closest to a coefficient of thermal expansion (CTE) of the housing material among focal thermo-optical coefficients of a plurality of possible lens materials, wherein the focal thermo-optical coefficient of a material indicates a change in focal length of a lens formed of that material due to temperature.