All purpose FLIR kit for aircraft

• US 6,274,868 B1
• Filed: 07/27/1999
• Issued: 08/14/2001
• Est. Priority Date: 07/23/1997
• Status: Expired due to Fees

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Wright, Richard A., Hall, John M.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): GAGLIARDI, ALBERT J
• Application Number:
  US09/361,805
• Time in Patent Office: 749 Days
• Field of Search: 250/332, 250/334, 250/353, 250/350, 359/351, 359/357, 359/356
• US Class Current: 250/332
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification

Abstract

FLIR kits are provided comprising optical and related components which can be commonly used for both navigational and targeting scenarios. Such components include a common detector interface, imaging optics, scanner, interlacer, filter wheel, and thermal reference sources with integrated chopper/rotator assembly, all of which when assembled form a stand-alone imaging sensor when combined with a common associated electronics subassembly. The kits are integrated into standard navigational and targeting platforms of the type found on the AH-64 Apache and RAH-66 Comanche attack helicopters.

Claims

1. In an aircraft turret including, a rigid disk-shaped floor plate, a rigid generally cylindrical shroud that covers said floor plate and defines an opening for a thin planar FLIR input window mounted normal to said floor plate with a width parallel to said plate at least twice its height, and a FLIR mounted on said floor plate coupled to control panels in said aircraft by means of one or more wire harnesses;

wherein said FLIR includes;

a folded optical axis of a length greater than the largest dimension of said turret and composed of separate sets of contiguous optic axis segments, said sets being defined by a number of replaceable kits, including at least an airkit and an afocal kit, each said kit having a series of optical elements the axes of which define said sets;

said airkit set including,

at least a portion of the three final segments of said folded optical axis including all of a middle segment along which are mounted three medium aperture far-infrared refractive lens elements on either side of an intermediate focal plane,

a scan folding mirror at one end of said middle segment defining an end portion of a segment in a preceding kit normal to said middle segment,

an interlace folding mirror at the opposite end of said middle segment defining a last segment normal to said middle segment coplanar and oppositely directed to said end portion, whereby said end portion, middle segment and output segment lie in a common airkit plane and said scan mirror is the only airkit element on said end portion;

only two far-infrared refractive lens elements mounted along said last segment; and

a far-infrared diode detector array behind a flat heat insulated far-infrared window in a cryogenic cooling dewar terminating said last segment.

2. A turret mounted FLIR according to claim 1;

wherein said airkit further includes;

a standard temperature sampling means mounted at a sample point along said optical axis between said intermediate focal plane and said interlace mirror to periodically insert a standard light signal at said sample point, while leaving said intermediate focal plane free.

3. A turret mounted FLIR according to claim 2;

wherein said airkit further includes;

an optical filter element without refractive power mounted at a filter point along said optical axis between said intermediate focal plane and said scan mirror to reduce the size requirement for said filter.

4. A turret mounted FLIR according to claim 1;

wherein said airkit further includes;

an optical filter element without refractive power mounted at a filter point along said optical axis between said intermediate focal plane and said scan mirror to reduce the size requirement for said filter, while leaving said intermediate focal plane free.

5. A turret mounted FLIR according to claim 1 wherein:

said refractive lens elements are formed from GaAs and ZnS, to reduce heating problems; and

one surface of each of said refractive lens elements is aspherically ground to provide minimum spherical aberration.

6. A turret mounted FLIR according to claim 1;

wherein;

said turret is the type used by an aircraft pilot for navigation;

said airkit common plane is parallel to said floor plate with said optic elements on said main and last output segments mounted as close to said plate as the dimensions of said optical elements will permit;

said shroud includes a remote controlled head mirror, facing said window, at least twice as wide as its height, attached inside the top of said shroud by means of a motorized horizontal axle parallel to said window and floor plate that rotates said head mirror approximately ±

45 degrees from its normal line of sight; and

said afocal kit further includes;

a deflection plane normal to said window and floor plate that includes a FLIR point substantially centered on the left half of said head mirror, as seen looking into said shroud with said floor plate horizontal;

said airkit being positioned so that said deflection plane includes said end portion;

an upward folding mirror centered on the intersection of said common airkit plane and said deflection plane at a deflection point below and slightly behind said head mirror;

whereby said optical axis of said FLIR comprises that of said airkit, an extension segment from said scan mirror to said upward folding mirror;

a vertical segment extending from said deflection point to said FLIR point and a FLIR input segment from said FLIR point to said window in said deflection plane that moves with said head mirror;

an auxiliary focal plane normal to said extension segment adjacent said upward folding mirror;

three navigation afocal refracting lenses mounted along said vertical segment to focus an image of a distant object on said auxiliary focal plane; and

two navigation relay refracting lenses mounted along said extension segment to reduce the size of said image to match the input aperture of said airkit.

7. A turret mounted FLIR according to claim 6;

further including;

a cylindrical cryogenic cooler coupled to said dewar with an axis of symmetry parallel to said main segment and one end overlapping said dewar;

a general electronics package mounted on said floor plate under said cooler, for powering and/or remotely controlling elements, such as said head mirror, said cooler, other electronic packages, cameras or test equipment within said turret as well as motors that move said turret; and

a computer electronics package mounted on said floor plate between said airkit and said shroud side wall furthest from said dewar, to generate and process electronic image data from said FLIR.

8. A turret mounted FLIR according to claim 7, further including:

a camera using an image intensifier tube for visible, near infrared and ultra-violet frequencies mounted on said floor plate below said head mirror with its optical axis meeting said head mirror at a camera point centered on the right half of said mirror, as seen through said window, thereby defining a turret camera optical axis normal to said window through said camera point;

an electronics package for said camera mounted on said floor plate between said dewar and said shroud side wall nearest said camera, said harnesses interconnecting said FLIR, Camera and all of said electronics packages whereby said camera and said FLIR can share storage, processing and display capabilities.

9. A turret mounted FLIR according to claim 6;

wherein;

said two navigation relay refracting lenses are mounted on a motorized slide to remotely adjust the focus at said auxiliary focal plane.

10. A turret mounted FLIR according to claim 6 wherein:

said refractive lens elements are formed from Germanium and ZnS, to reduce chromatic aberration; and

one surface of each of said refractive lens elements is aspherically ground to provide minimum spherical aberration.

11. A turret mounted FLIR according to claim 1;

wherein;

said turret is the type used by a gunner for targeting;

said airkit is mounted with said main segment perpendicular to said floor plate and said airkit output segment parallel and as close as possible to said plate, whereby said airkit end portion segment lies in a target plane parallel to said floor plate near the top of said shroud and parallel to a diametrical reference relay line in said target plane through the axis of symmetry of said plate tilted 30 degrees to said window, the right end of said relay line being furthest from said window; and

said kits also include a relay lens kit, which further includes;

a cross segment of said optical axis normally intersected by the right end of said relay line with a first and second relay folding mirrors, mounted at first and second tips of said cross segment, normal to said floor plate and closely adjacent to the right sidewall of said shroud, defining a folded U-shaped section of said optical axis with input and output relay segments parallel to said relay line from first and second tips, respectively, said target plane also partially defining a window segment of said optical axis normal to said relay input segment from said first tip extending through the left side of said window;

said airkit having cylindrical-shaped scan and thermal standard motors with axial lengths about equal to said dewar and being normal to all said airkit axial segments, said airkit end portion being collinear with said relay input segment and said airkit being located as near to the right end of said relay line as the motor dimensions permit;

special folding mirror means mounted beyond the free left tip of said relay input segment to redirect radiation entering along said window segment to said relay input segment;

a relay focal plane between said relay folding mirrors,

first and second pairs of targeting refractive relay lens elements mounted, respectively, on said relay input and output segments;

said first pair forming a high quality image at said relay focal plane and said second pair forming an image to fit said airkit aperture, thereby providing a medium or other field of view depending on the structure of said special folding mirror means.

12. A turret mounted FLIR according to claim 11;

wherein said special folding mirror means includes;

a series of four afocal mirrors, with flat back surfaces adjacent to and facing the top of the sidewall of said shroud;

said back surfaces being normal to said floor plate with each said afocal mirror substantially intersecting a different one of four quadrants of said target plane;

the first, second and fourth of said afocal mirrors having aspherically ground areas on their front surface, the remainder of said front surfaces being flat, whereby said optical axis is folded into first second and third additional reflective segments between said window segment and said relay input segment;

said afocal mirrors forming a mirror focal plane, with a high quality image, between the center of said third segment and said third afocal mirror;

said first afocal mirror having a dimension parallel to the symmetry axis of said floor plate greater than half the same dimension of said shroud and being centered on said window segment;

said fourth afocal mirror having a dimension parallel to the symmetry axis of said floor plate almost twice the same dimension of the largest lens in said relay kit and being coaxial with said relay input segment;

said first, third and fourth reflective segments, respectively, being greater than half the diameter of said floor plate and said fourth segment being collinear with said relay input segment;

said second mirror in said series being arranged to redirect said optical axis over said second reflective segment greater than half the other said reflective segments, thereby providing a very long focal length and a ury narrow field of view FLIR.

13. A turret mounted FLIR according to claim 12;

wherein said special folding mirror means further includes;

a switch mirror centered on the intersection of said relay input segment with said window segment;

said switch mirror being mounted on a primary remote controlled motor means for removing said plane folding mirror entirely from the optical path in response to a primary signal, whereby said FLIR optics may provide a remote controlled medium or narrow angle of view.

14. A turret mounted FLIR according to claim 13;

wherein;

a first pair of afocal lenses are mounted on said window segment by a secondary remote controlled motor means for removing said first pair from said optical path in response to a secondary signal; and

a second pair of afocal lenses are mounted on said relay input segment by a tertiary remote controlled motor means for removing said second pair from said optical axis in response to a tertiary signal;

whereby said FLIR optics may provide a remote controlled wide, medium or narrow angle of view.

15. A turret mounted FLIR according to claim 11;

wherein said special folding mirror means includes;

a primary plane folding mirror mounted centered on the intersection of said relay input segment with said window segment, thereby providing at least a medium field of view FLIR.

16. A turret mounted FLIR according to claim 11;

wherein;

a first pair of refractive afocal lenses are mounted on said window segment by a secondary remote controlled motor means for focusing and removing said first pair from said optical path in response to focusing and removing secondary signals, respectively; and

a second pair of refractive afocal lenses are mounted on said relay input segment by a tertiary remote controlled motor means for focusing and removing said second pair from said optical axis in response to a tertiary focusing and signals, respectively;

whereby said FLIR optics may provide a remote controlled wide or medium angle of view.

17. A turret mounted FLIR according to claim 16 wherein:

said refractive lens elements are formed from GaAs and ZnS, to reduce heating problems; and

one surface of each of said refractive lens elements is aspherically ground to provide minimum spherical aberration.

18. A turret mounted FLIR according to claim 11, wherein:

at least one of said first and second pairs of targeting refractive relay lens elements are mounted on a motorized slide to remotely adjust the focus at said auxiliary focal plane.

19. A turret mounted FLIR according to claim 11 wherein:

said refractive lens elements are formed from GaAs and ZnS, to reduce heating problems; and

one surface of each of said refractive lens elements is aspherically ground to provid minimum spherical aberration.

20. A turret mounted FLIR according to claim 1;

wherein;

a pair of said three medium aperture lens elements are mounted on a motorized slide to remotely adjust the focus at said intermediate focal plane.