Optical payload with folded telescope and cryocooler

• US 8,687,111 B2
• Filed: 05/11/2009
• Issued: 04/01/2014
• Est. Priority Date: 05/12/2008
• Status: Expired due to Fees

• Current Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: McKaughan, Stephen V., Rombult, Philip A., Campbell, Robert J. Jr.
• Primary Examiner(s): SPINKS, ANTOINETTE T
• Application Number:
  US12/463,858
• Publication Number:
  US 20090284644A1
• Time in Patent Office: 1,786 Days
• Field of Search: 348/373, 348/207.99, 348/335
• US Class Current: 348/373
• 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 comprising:

a mid-infrared primary video camera for imaging a target with respect to a primary point axis of the camera, the camera including a folded narrow field of view fixed first magnification telescopic optical system having a telescope optical axis that is not parallel to the primary pointing axis; and

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

K, wherein the folded cryocooler includes a rotary DC motor for driving both a gas compressor piston and a regenerator piston through a folded linkage and wherein the folded linkage reciprocally drives a regenerator piston along a linear axis that is parallel with a rotation axis of the DC motor.

2. The optical payload of claim 1 wherein the folded narrow field of view fixed magnification telescopic optical system comprises two fold mirrors each disposed at a compound angle with respect to the primary pointing axis, and

wherein the mid-infrared primary video camera includes an actuator configured to move along the telescope optical axis to actuate the first magnification telescopic optical system to focus an image on the primary focal plane array.

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

4. The optical payload of claim 3 further comprising a secondary video camera including a fixed magnification wide field of view optical system for forming a secondary image of the target onto a secondary focal plane array at a second magnification, that is less than the first magnification, wherein the secondary focal plane array 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 rotatably attached to a support structure for housing a first portion of a payload electrical control system in a cylindrical top section of the yoke assembly that is formed by a thin annular wall surrounding a hollow electronics cavity that includes a circular top opening for installing electrical control systems therein;

a spherical payload assembly rotatably attached to the yoke assembly for housing the primary video camera, the folded cryocooler, the secondary video camera and a second portion of the payload electrical control system therein; and

a primary drive system configured to rotate the yoke assembly about an azimuth axis (A) and to rotate the spherical payload assembly about an elevation axis (E) for pointing the primary pointing axis.

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

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

11. The optical payload of claim 4 further comprising:

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

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

a communication processor in communications with a network switch for merging the corrected primary and secondary images into a single network packetized data stream suitable for transmission over a radio transceiver 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.

7. The optical payload of claim further comprising a plurality of circular PC boards each having a circular peripheral edge 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 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 fixedly attached to the thin annular wall and disposed to contact thermally and electrically conductive pads formed on each of the plurality of PC boards wherein the mounting blocks fixedly supporting each of the plurality of PC boards inside the hollow cavity and provide a thermally and electrically conductive path between each of the plurality of PC boards and the thin annular wall.

9. The optical payload of claim 8 further comprising:

a laser rangefinder transmitter module comprising a rangefinder laser for emitting a pulsed laser rangefinder beam and a small aperture telescopic lens system configured to substantially collimate and point the laser rangefinder beam at the target; and

a laser target designator module comprising a designator laser for emitting a pulsed laser target designator beam, a large aperture telescopic lens system configured to substantially collimate and point the designator beam at the target, a laser rangefinder receiver module for generating a photocurrent responsive to an 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 and the designator laser for directing the pulsed laser target designator beam from the designator laser to the large aperture telescopic lens system; and

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

12. An optical payload comprising:

a mid-infrared primary video camera for imaging a target with respect to a primary pointing axis of the camera, the camera including a folded narrow field of view fixed magnification telescopic optical system having a telescope optical axis that is not parallel to the primary pointing axis;

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

K, the folded cryocooler including a rotary motor driving both a compressor piston and a regenerator piston, wherein the rotary motor drives the regenerator piston through a linear axis that is parallel with a rotary axis of the rotary motor;

a long-infrared secondary video camera including a fixed magnification wide field of view optical system for forming a secondary image of the target; and

a visible-light third video camera including an optical system for forming a tertiary image of the target.

13. The optical payload of claim 12 further comprising:

a laser rangefinder transmitter module comprising a rangefinder laser for emitting a pulsed laser rangefinder beam directed at the target;

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

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

wherein the mid-infrared primary video camera includes an actuator configured to move along the telescope optical axis to actuate the folded narrow field of view fixed magnification telescopic optical system to focus an image on the primary focal plane array.

14. The optical payload of claim 13 further comprising a laser target designator module comprising a designator laser for emitting a pulsed laser target designator beam directed at the target.

15. The optical payload of claim 14 wherein the laser target designator module comprises:

the designator laser;

the laser rangefinder receiver module;

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

the signal processor for processing photo current signals generated thereby to determine a range between the optical payload and the target

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

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

16. The optical payload of claim 15 wherein both the first optical elements and the second optical elements include a beam splitter configured to transmit the laser target designator beam and to reflect the energy of the pulsed laser rangefinder beam that is reflected by the target.

17. The optical payload of claim 16 wherein the first optical elements further comprise two mirrors disposed between the beam splitter and the large aperture telescopic lens system.

18. The optical payload of claim 17 wherein the second optical elements further comprise a mirror and a focusing lens set for focusing the energy of the pulsed laser rangefinder beam that is reflected by the target area onto an active area of the laser rangefinder receiver module.

19. The optical payload of claim 18 wherein the beam splitter comprises a dichroic filter configured with a maximum spectral transmission substantially matched with a spectral emission of the designator laser and further configured with a maximum spectral reflectance substantially matched with the spectral emission of the rangefinder laser.

20. The optical payload of claim 19 further comprising a fiber optic element extending between the laser rangefinder transmitter module and the laser designator module for directing at least a portion of the energy of each pulse of the laser rangefinder beam onto an active area of the laser rangefinder receiver module.

21. The optical payload of claim 20 further comprising:

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

a spherical payload assembly rotatably attached to the yoke assembly for housing the primary video camera, the folded cryocooler, the secondary video camera, the third video camera, the laser rangefinder transmitter module, the laser target designator module and a second portion of the payload electrical control system therein; and

a primary drive system configured to rotate the yoke assembly about an azimuth axis (A) and to rotate the spherical payload assembly about an elevation axis (E) for pointing the primary pointing axis at the target.

22. The optical payload of claim 21 wherein the spherical payload assembly is formed with a spherical external housing having a housing outside diameter of less than 190 mm.