Reentry vehicle interceptor with IR and variable FOV laser radar

• US 20040021852A1
• Filed: 02/03/2003
• Published: 02/05/2004
• Est. Priority Date: 02/04/2002
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: DeFlumere, Michael E.
• Granted Patent: US 6,741,341 B2
• Time in Patent Office: Days
• US Class Current: 356/141.1
• CPC Class Codes: F41G 7/008 Combinations of different guidance systems
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2246 Active homing systems, i.e. comprising both a transmitter and a receiver
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4813 Housing arrangements

Abstract

A dual mode seeker for intercepting a reentry vehicle or other target is disclosed. In one embodiment, the seeker is configured with an onboard 3D ladar system coordinated with an onboard IR detection system, where both systems utilize a common aperture. The IR and ladar systems cooperate with a ground based reentry vehicle detection/tracking system for defining a primary target area coordinate and focusing the IR FOV thereon. The IR system obtains IR image data in the IR FOV. The ladar system initially transmits with a smaller laser FOV to illuminate possible targets, rapidly interrogating the IR FOV. The ladar system obtains data on each possible target to perform primary discrimination assessments. Data fusion is employed to resolve the possible targets as between decoys/clutter and a reentry vehicle. The laser FOV is expandable to the IR FOV. Robust and reliable discrimination is obtained at high altitudes.

Claims

1. A dual mode seeker for intercepting a reentry vehicle, and configured with an onboard ladar system coordinated with an onboard IR system, the seeker comprising:

a telescope having two or more mirrors forming a folded optical path that is adapted to receive IR and laser return information collected at a common aperture;

a dichroic filter placed in the folded optical path, and adapted for separating the IR return information from the laser return information;

an IR detector adapted to detect the IR return information separated by the dichroic filter, wherein the IR return information is received from a field of view associated with the IR system; and

a laser detector adapted to detect the laser return information separated by the dichroic filter, the laser return information relevant to one or more objects included in the field of view.

2. The seeker of claim 1 further comprising:

a processing module configured to form three dimensional images of one or more objects included in the field of view based on the detected laser return information.

3. The seeker of claim 1 further comprising:

a processing module configured to perform discrimination assessments based on discrimination parameters including at least one of relative velocity, track, and separation data.

4. The seeker of claim 1 further comprising:

a processing module configured to perform data fusion between at least two of target object map data, three dimensional laser image data, and two dimensional IR image data.

5. The seeker of claim 1 wherein at least one of the IR and ladar systems are adapted to cooperate with a ground based reentry vehicle detection/tracking system configured to define a primary target area coordinate.

6. The seeker of claim 1 wherein the ladar system is configured with a variable field of view that is expandable to substantially match the field of view associated with the IR system.

7. The seeker of claim 6 wherein the variable field of view associated with the ladar system is expandable toward the field of view associated with the IR system when at least one of closing velocity, track angle, or target size subtends the laser system'"'"'s field of view.

8. The seeker of claim 6 wherein the variable field of view associated with the ladar system is initially smaller than the field of view associated with the IR system during engagement, and the ladar system is adapted to systematically interrogate the field of view associated with the IR system to discriminate objects located therein.

9. The seeker of claim 1 wherein the ladar system is configured to operate as at least one of an angle, angle, range direct detection type system, and a pulsed Doppler coherent detection type system.

10. The seeker of claim 1 wherein the laser detector includes an array and the ladar system is configured to operate as a hybrid detection system, where a first portion of the laser detector array performs coherent detection, and second portion of the laser detector array performs linear mode direct detection.

11. The seeker of claim 1 wherein the ladar system includes a laser and one or more steering mirrors for pointing the laser at objects in the field of view associated with the IR detector.

12. The seeker of claim 11 wherein outgoing laser pulses from the laser share the common aperture with the IR and laser return information.

13. The seeker of claim 11 wherein outgoing laser pulses from the laser travel a limited portion of the folded optical path.

14. The seeker of claim 1 further including a bandpass filter operatively coupled between the laser detector and the dichroic filter, and adapted for reducing the background into the laser detector.

15. The seeker of claim 1 wherein the laser detector is configured with an avalanche photo diode optically coupled with a fiber, and X-Y table motors for moving the fiber to a number of positions, thereby forming a virtual detector array.

16. The seeker of claim 15 wherein the laser detector further includes a range counter that is adapted to receive data from the avalanche photo diode for each virtual pixel location, thereby enabling a range calculation with each pulse of laser return information on a pixel by pixel basis.

17. The seeker of claim 1 wherein the laser detector is configured with an avalanche photodiode detector focal plane array of a predefined dimension.

18. The seeker of claim 17 wherein the laser detector further includes a range counter that is adapted to receive pixel data in parallel from the avalanche photodiode detector focal plane array, thereby enabling a full complement of data for range calculations with each pulse of laser return information.

19. The seeker of claim 18 wherein for each pulse of laser return information, range data associated with pixels of the focal plane array avalanche photodiode detector is provided in parallel by the range counter to a processor, so that pixel data processing can be performed.

20. The seeker of claim 1 wherein each of the laser and IR detectors are associated with a resolution, and the resolution of the laser detector is at least two times higher than the resolution of the IR detector.

21. A dual mode seeker for intercepting a reentry vehicle, and configured with an onboard ladar system coordinated with an onboard IR system, the seeker comprising:

a telescope having two or more mirrors forming a folded optical path that is adapted to receive IR and laser return information collected at a common aperture;

a dichroic filter placed in the folded optical path, and adapted for separating the IR return information from the laser return information;

a laser detector adapted to detect the laser return information separated by the dichroic filter, the laser return information relevant to one or more objects included in a field of view associated with the IR system; and

a first processing module configured to perform data fusion between at least two of target object map data, three dimensional laser image data, and two dimensional IR image data.

22. The seeker of claim 21 further comprising:

a second processing module configured to form three dimensional images of one or more objects included in the field of view based on the detected laser return information.

23. The seeker of claim 21 further comprising:

a third processing module configured to perform discrimination assessments based on discrimination parameters including at least one of relative velocity, track, and separation data.

24. The seeker of claim 21 wherein the laser detector is configured with an avalanche photodiode detector focal plane array of a predefined dimension.

25. The seeker of claim 24 wherein the laser detector further includes a range counter that is adapted to receive-pixel data in parallel from the avalanche photodiode detector focal plane array, thereby enabling a full complement of data for range calculations with each pulse of laser return information.

26. The seeker of claim 24 wherein for each pulse of laser return information, range data associated with pixels of the focal plane array avalanche photodiode detector is provided in parallel by the range counter to a pixel data process module.

27. The seeker of claim 21 wherein the ladar system is configured with a variable field of view that is expandable to substantially match the field of view associated with the IR system.

28. The seeker of claim 27 wherein the variable field of view associated with the ladar system is expandable toward the field of view associated with the IR system when at least one of closing velocity, track angle, or target size subtends the laser system'"'"'s field of view.

29. The seeker of claim 27 wherein the variable field of view associated with the ladar system is initially smaller than the field of view associated with the IR system during engagement, and the ladar system is adapted to systematically interrogate the field of view associated with the IR system to discriminate objects located therein.

30. A dual mode seeker for intercepting a reentry vehicle, and configured with an onboard ladar system coordinated with an onboard IR system, the seeker comprising:

a telescope having two or more mirrors forming a folded optical path that is adapted to receive IR and laser return information collected at a common aperture;

a dichroic filter placed in the folded optical path, and adapted for separating the IR return information from the laser return information; and

a laser detector adapted to detect the laser return information separated by the dichroic filter, the laser return information relevant to one or more objects included in a field of view associated with the IR system.

31. The seeker of claim 30 wherein the ladar system is configured with a variable field of view that is expandable to substantially match the field of view associated with the IR system.

32. The seeker of claim 31 wherein the variable field of view associated with the ladar system is expandable toward the field of view associated with the IR system when at least one of closing velocity, track angle, or target size subtends the laser system'"'"'s field of view.

33. The seeker of claim 31 wherein the variable field of view associated with the ladar system is initially smaller than the field of view associated with the IR system during engagement, and the ladar system is adapted to systematically interrogate the field of view associated with the IR system to discriminate objects located therein.

34. The seeker of claim 30 wherein the ladar system is configured to operate as at least one of an angle, angle, range direct detection type system, and a pulsed Doppler coherent detection type system.

35. The seeker of claim 30 wherein the laser detector includes an array and the ladar system is configured to operate as a hybrid detection system, where a first portion of the laser detector array performs coherent detection, and second portion of the laser detector array performs linear mode direct detection.

36. The seeker of claim 30 wherein outgoing laser pulses share the common aperture with the IR and laser return information.

37. The seeker of claim 30 wherein outgoing laser pulses travel a limited portion of the folded optical path.

38. The seeker of claim 30 wherein the laser detector is configured with an avalanche photodiode detector focal plane array of a predefined dimension.

39. The seeker of claim 38 wherein the laser detector further includes a range counter that is adapted to receive pixel data in parallel from the avalanche photodiode detector focal plane array, thereby enabling a full complement of data for range calculations with each pulse of laser return information.

40. The seeker of claim 39 wherein for each pulse of laser return information, range data associated with pixels of the focal plane array avalanche photodiode detector is provided in parallel by the range counter to a processor, so that pixel data processing can be performed.