Optical Payload with Folded Telescope and Cryocooler

• US 20090284644A1
• Filed: 05/11/2009
• Published: 11/19/2009
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Rombult, Philip A., Campbell, Robert J. JR., McKaughan, Stephen V.
• Granted Patent: US 8,687,111 B2
• Time in Patent Office: Days
• US Class Current: 348/348
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: H04N 23/50 Constructional details
• CPC Class Codes: H04N 23/661 Transmitting camera control signals through networks, e.g. control via the Internet
• CPC Class Codes: H04N 23/69 Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• CPC Class Codes: H04N 23/90 Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A compact optical payload for an unmanned aircraft includes two infrared cameras for wide and narrow field viewing, a daylight color camera, a laser pointer and a laser range finder.

Claims

1. An optical payload (100) for directing a primary pointing axis at a target area (325) comprising:

a primary video camera (310) including a folded narrow field of view fixed magnification telescopic optical system (350) for forming a primary image of the target area (325) onto a primary focal plane array (365) at a first magnification and wherein the primary focal plane array (365) comprises elements suitable for rendering a primary video image over a mid-infrared spectral range; and

,

a folded cryocooler (370) formed integrally with the primary video camera (310) for cooling the primary focal plane array (365) to an operating temperature below 90°

K.

2. The optical payload of claim 1 wherein the folded narrow field of view fixed magnification telescopic optical system (350) comprises two fold mirrors (920) and (925) each disposed at a compound angle with respect to an optical axis of the telescopic optical system (350).

3. The optical payload of claim 2 wherein the folded cryocooler (370) comprises a rotary DC motor (930) for driving a gas compressor and a folded linkage, each housed inside a crankcase (935), and wherein the folded linkage reciprocally drives a regenerator piston (940) along a linear axis that is parallel with a rotation axis of the DC motor (940).

4. The optical payload of claim 3 further comprising a secondary video camera (315) including a fixed magnification wide field of view optical system (375) for forming a secondary image of the target area (325) onto a secondary focal plane array (385) at a second magnification, that is less than the first magnification, wherein the secondary focal plane array (385) comprises elements suitable for rendering the secondary video image over a long-infrared spectral range.

5. The optical payload of claim 4 further comprising:

a cylindrical yoke assembly (105) rotatably attached to a support structure (145) for housing a first portion of a payload electrical control system (700) in a cylindrical top section (150) of the yoke assembly (105) that is formed by a thin annular wall (155) surrounding a hollow electronics cavity (160) that includes a circular top opening for installing electrical control systems therein;

a spherical payload assembly (110) rotatably attached to the yoke assembly (105) for housing the primary video camera (310), the folded cryocooler (370), the secondary video camera (315) and a second portion of the payload electrical control system (700) therein; and

,

a primary drive system (600) configured to rotate the yoke assembly (105) about an azimuth axis (A) and to rotate the spherical payload assembly (110) about an elevation axis (E) for pointing the primary pointing axis (130), comprising a central ray of the folded narrow field of fixed magnification telescopic optical system (350), at the target area (325).

6. The optical payload of claim 5 further comprising a slip ring assembly (330) disposed between the payload assembly (110) and the yoke assembly (105) for exchanged electrical signals there between.

7. The optical payload of claim 6 further comprising a plurality of circular PC boards each having a circular peripheral edge (855) and opposing top and bottom surfaces populated with surface mounted electrical components and electrical connectors, wherein each of the plurality of circular PC boards is disposed within the circular cavity (160) with top and bottom surfaces thereof substantially normal to the azimuth axis (A).

8. The optical payload of claim 7 further comprising a plurality of mounting blocks (860, 865) fixedly attached to the thin annular wall (155) and disposed to contact thermally and electrically conductive pads (850) formed on each of the plurality of PC boards wherein the mounting blocks (860, 865) fixedly supporting each of the plurality of PC boards inside the hollow cavity (160) and provide a thermally and electrically conductive path between each of the plurality of PC boards and the thin annular wall (155).

9. The optical payload of claim 8 further comprising:

a laser rangefinder transmitter module (340) comprising a rangefinder laser (341) for emitting a pulsed laser rangefinder beam (425) and a small aperture telescopic lens system (342) configured to substantially collimate and point the laser rangefinder beam (425) at the target area; and

,

a laser target designator module (345) comprising a designator laser (346) for emitting a pulsed laser target designator beam (416), a large aperture telescopic lens system (390) configured to substantially collimate and point the designator beam (416) at the target area, a laser rangefinder receiver module (430) for generating a photocurrent responsive to energy of the pulsed laser range finder beam falling thereon, first optical elements disposed along a first optical path between the large aperture telescopic lens system (390) and the designator laser (346) for directing the pulsed laser target designator beam (416) from the designator laser (346) to the large aperture telescopic lens system (390); and

, second optical elements disposed along a second optical path between the large aperture telescopic lens system (390) and the laser rangefinder receiver module (430) for directing energy of the a pulsed laser rangefinder beam (425) that is reflected by the target area and collected by the large aperture telescopic lens system (390) onto an active area of the laser rangefinder receiver module (430).

10. The optical payload of claim 4 further comprising a third video camera (335) including an optical system (392) for forming a tertiary image of the target area (325), wherein the third video camera (335) is configured to render the tertiary video image of the target area (325) over a visible spectral range.

11. The optical payload of claim 4 further comprising:

area master controller (760) for correcting a primary video image of the target area and a secondary video image of the target area;

a network switch (816) for receiving each of the corrected primary and secondary video images therein; and

,

a communication processor (820) in communications with a network switch (816) for merging the corrected primary and secondary images into a single network packetized data stream suitable for transmission over a radio transceiver (705) wherein data packets associated with the primary video image are addressed to a first IP address and data packets associated with the secondary video image are addressed to a second IP address.

12. The optical payload of claim 11 further comprising:

a third digital processor (806) in communication with each of the first digital processor (804) and the network switch (816) for compressing the corrected primary video image; and

,

a fourth digital processor (818) in communication with each of the second digital processor (812) and the network switch (816) for compressing the corrected secondary video image.

13. An optical payload (100) for directing a primary pointing axis at a target area (325) comprising:

a primary video camera (310) including a folded narrow field of view fixed magnification telescopic optical system (350) for forming a primary image of the target area (325) onto a primary focal plane array (365) at a first magnification and wherein the primary focal plane array (365) comprises elements suitable for rendering a primary video image over a mid-infrared spectral range;

a folded cryocooler (370) formed integrally with the primary video camera (310) for cooling the primary focal plane array (365) to an operating temperature below 90°

K;

a secondary video camera (315) including a fixed magnification wide field of view optical system (375) for forming a secondary image of the target area (325) onto a secondary focal plane array (385) at a second magnification, that is less than the first magnification, wherein the secondary focal plane array (385) comprises elements suitable for rendering the secondary video image over a long-infrared spectral range; and

,

a third video camera (335) including an optical system (392) for forming a tertiary image of the target area (325) wherein the third video camera (335) is configured to render the tertiary video image of the target area (325) over a visible spectral range.

14. The optical payload of claim 13 further comprising:

a laser rangefinder transmitter module (340) comprising a rangefinder laser (341) for emitting a pulsed laser rangefinder beam (425) directed at the target area;

a laser rangefinder receiver module (430) for generating a photocurrent responsive to energy of the pulsed laser rangefinder beam (425) that is reflected by the target area and directed onto an active area of the laser rangefinder receiver module (430); and

,

a signal processor (424) in communication with the laser rangefinder receiver module (430) for processing photo current signals generated in response to the energy of the pulsed laser rangefinder beam (425) that is reflected by the target area to determine a range between the optical payload and the target area.

15. The optical payload of claim 14 further comprising a laser target designator module (345) comprising a designator laser (346) for emitting a pulsed laser target designator beam (416) directed at the target area (325).

16. The optical payload of claim 15 wherein the laser target designator module (345) comprises:

the designator laser (346);

the laser rangefinder receiver module (430);

a large aperture telescopic lens system (390) configured to substantially collimate and point the designator beam (416) at the target area and to collect the energy of the pulsed laser rangefinder beam (425) that is reflected by the target area;

the signal processor (424) for processing photo current signals generated thereby to determine a range between the optical payload and the target area;

first optical elements disposed along a first optical path between the large aperture telescopic lens system (390) and the designator laser (346) for directing the pulsed laser target designator beam (416) from the designator laser (346) to the large aperture telescopic lens system (390); and

,

second optical elements disposed along a second optical path between the large aperture telescopic lens system (390) and the laser rangefinder receiver module (430) for directing the energy of the a pulsed laser rangefinder beam (425) that is reflected by the target area and collected by the large aperture telescopic lens system (390) onto the laser rangefinder receiver module (430).

17. The optical payload of claim 16 wherein both the first optical elements and the second optical elements include a beam splitter (415) configured to transmit the laser target designator beam (416) and to reflect the energy of the pulsed laser rangefinder beam (425) that is reflected by the target area.

18. The optical payload of claim 17 wherein the first optical elements further comprise two mirrors (410) disposed between the beam splitter (415) and the large aperture telescopic lens system (390).

19. The optical payload of claim 18 wherein the second optical elements further comprise a mirror (410) and a focusing lens set (420) for focusing the energy of the pulsed laser rangefinder beam (425) that is reflected by the target area onto an active area of the laser rangefinder receiver module (430).

20. The optical payload of claim 19 wherein the beam splitter (415) comprises a dichotic filter configured with a maximum spectral transmission substantially matched with a spectral emission of the designator laser (346) and further configured with a maximum spectral reflectance substantially matched with the spectral emission of the rangefinder laser (341).

21. The optical payload of claim 20 further comprising a fiber optic element (422) extending between the laser rangefinder transmitter module (340) and the laser designator module (345) for directing at least a portion of the energy of each pulse of the laser rangefinder beam (425) onto an active area of the laser rangefinder receiver module (340).

22. The optical payload of claim 21 further comprising:

a cylindrical yoke assembly (105) rotatably attached to a support structure (145) for housing a first portion of a payload electrical control system (700) in a hollow cylindrical top section (150) thereof;

a spherical payload assembly (110) rotatably attached to the yoke assembly (105) for housing the primary video camera (310), the folded cryocooler (370), the secondary video camera (315), the third video camera (335), the laser rangefinder transmitter module (340), the laser target designator module (345) and a second portion of the payload electrical control system (700) therein; and

,

a primary drive system (600) configured to rotate the yoke assembly (105) about an azimuth axis (A) and to rotate the spherical payload assembly (110) about an elevation axis (E) for pointing a primary pointing axis (130), comprising a central ray of the folded narrow field of fixed magnification telescopic optical system (350), at the target area (325).

23. The optical payload of claim 22 wherein the spherical payload assembly is formed with a spherical external housing having a housing outside diameter of less than 190 mm.