Optical system for a wide field of view staring infrared sensor having improved optical symmetry
First Claim
1. A wide-angle infrared radiation (IR) imaging system having an entrance aperture for admitting IR from a scene, comprising:
- a dewar containing a coldshield that encloses a cooled IR detector disposed at an image plane, said dewar comprising a dewar window, an optical axis of said IR imaging system passing through said dewar window and said image plane;
a plurality of uncooled optical elements disposed along said optical axis between said entrance aperture and said dewar window; and
a plurality of reflector segments disposed around said optical axis between said dewar window and said entrance aperture, each of said reflector segments having a reflective surface facing said dewar window, where an opening through an outermost reflector segment furthest from said dewar window defines an effective cooled aperture stop of said IR imaging system, and where at least one of said optical elements is disposed between said effective cooled aperture stop and another one of said reflector segments that is located nearer to said dewar window.
1 Assignment
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Accused Products
Abstract
A wide-angle IR imaging system (1A) has an entrance aperture (40) for admitting IR from a scene and a dewar (4A) that contains a coldshield (3) that encloses a cooled IR detector (2) disposed at an image plane (2A). The dewar includes a dewar window (4), and an optical axis of the IR imaging system passes through the dewar window and the image plane. The IR imaging system further includes a plurality of uncooled optical elements (22, 24, 26, 28) disposed along the optical axis between the entrance aperture and the dewar window, and a plurality of generally annular reflector segments (18A, 18B) disposed around the optical axis between the dewar window and the entrance aperture. Each of the reflector segments has a reflective surface that faces the dewar window. An opening through an outermost reflector segment furthest from the dewar window defines an effective cooled aperture stop, or warm stop (20A) of the IR imaging system, and at least one of the optical elements (22) is disposed between the effective cooled aperture stop and another one of the reflector segments (18A) that is located nearer to the dewar window. In the preferred embodiment the at least one optical element, and the reflector segment that is located nearer to the dewar window, are comprised of a single monolithic body (31) that has a compound optical surface.
29 Citations
36 Claims
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1. A wide-angle infrared radiation (IR) imaging system having an entrance aperture for admitting IR from a scene, comprising:
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a dewar containing a coldshield that encloses a cooled IR detector disposed at an image plane, said dewar comprising a dewar window, an optical axis of said IR imaging system passing through said dewar window and said image plane; a plurality of uncooled optical elements disposed along said optical axis between said entrance aperture and said dewar window; and a plurality of reflector segments disposed around said optical axis between said dewar window and said entrance aperture, each of said reflector segments having a reflective surface facing said dewar window, where an opening through an outermost reflector segment furthest from said dewar window defines an effective cooled aperture stop of said IR imaging system, and where at least one of said optical elements is disposed between said effective cooled aperture stop and another one of said reflector segments that is located nearer to said dewar window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for operating a wide-angle infrared radiation (IR) imaging system having an entrance aperture for admitting IR from a scene, said IR imaging system having a dewar that contains a coldshield that encloses a cooled IR detector array disposed at an image plane, said dewar comprising a dewar window, where an optical axis of said IR imaging system passes through said dewar window to said image plane, the method comprising:
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providing along said optical axis between said entrance aperture and said dewar window a plurality of uncooled optical elements and a plurality of reflector segments, each of said reflector segments having a generally annular reflective surface facing said dewar window, said reflective surface surrounding an IR transmission path region through said reflector segment; defining an effective cooled aperture stop of said IR imaging system as being coincident with said IR transmission path region through a reflector segment that is furthest from said dewar window; and locating at least one of said optical elements between said effective cooled aperture stop and another one of said reflector segments that is located nearer to said dewar window. - View Dependent Claims (20, 21, 22, 23, 24)
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25. An infrared radiation (IR) imaging system having an entrance aperture for admitting IR from a scene, said IR imaging system comprising a dewar that contains a coldshield that encloses a cooled IR detector array disposed at an image plane, said dewar comprising a dewar window, where an optical axis of said IR imaging system passes through said dewar window to said image plane;
- a plurality of uncooled optical elements and a plurality of reflector segments disposed along said optical axis between said entrance aperture and said dewar window, each of said reflector segments having a generally annular reflective surface facing said dewar window, said reflective surface surrounding an IR transmission path region through said reflector segment;
where an effective cooled aperture stop of said IR imaging system is coincident with said IR transmission path region through a reflector segment that is furthest from said dewar window; and
where at least one of said optical elements is disposed between said effective cooled aperture stop and another one of said reflector segments that is located nearer to said dewar window. - View Dependent Claims (26, 27, 28, 29, 30)
- a plurality of uncooled optical elements and a plurality of reflector segments disposed along said optical axis between said entrance aperture and said dewar window, each of said reflector segments having a generally annular reflective surface facing said dewar window, said reflective surface surrounding an IR transmission path region through said reflector segment;
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31. A wide-angle infrared radiation (IR) imaging system having an entrance aperture for admitting IR from a scene and an image plane upon which the scene is imaged, comprising:
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a dewar that encloses a cooled IR detector disposed at the image plane, said dewar comprising an outer window, a coldshield, and said detector; a multi-element lens that comprises a plurality of uncooled optical elements disposed along the optical axis between said entrance aperture and said dewar window; an optical stop disposed within said uncooled optical elements such that lens optical power is distributed on both sides of the optical stop; and at least one reflector element comprising at least one inner opening and at least one surface having a generally toroidal surface shape, and having one of the at least one inner openings placed substantially coincident with said optical stop. - View Dependent Claims (32, 33, 34, 35, 36)
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Specification