INFRARED SPATIAL MODULATOR FOR SCENE-BASED NON-UNIFORMITY IMAGE CORRECTION AND SYSTEMS AND METHODS RELATED THERETO

• US 20120199689A1
• Filed: 02/04/2011
• Published: 08/09/2012
• Est. Priority Date: 02/04/2011
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Burkland, Michael K.
• Granted Patent: US 8,872,111 B2
• Time in Patent Office: Days
• US Class Current: 244/3.16
• CPC Class Codes: F42B 15/01 Arrangements thereon for guidance or control steering arrangements F42B10/60; aircraft flight control B64C; guidance systems other than those installed aboard F41G7/00, F41G9/00; locating by use of radio or other waves G01S; flight control in general G05D1/00; computer aspects G06]

Abstract

Embodiments of an infrared spectral modulator for scene-based non-uniformity image correction are generally disclosed herein. The spectral modulator may be suitable for use in a system for navigating an object having a flight path comprising an infrared sensor having an optical path; an infrared modulator in the optical path of the infrared sensor, wherein the infrared modulator is configured to allow the infrared sensor to perform in situ, real-time, scene-based non-uniformity correction; and a guidance system within the object, wherein the guidance system can adjust the flight path of the object based on the non-uniformity correction.

Claims

1. A system for navigating an object having a flight path comprising:

an infrared sensor having an optical path;

an infrared modulator in the optical path of the infrared sensor, wherein the infrared modulator is configured to allow the infrared sensor to perform in situ, scene-based non-uniformity correction; and

a guidance system within the object, wherein the guidance system can adjust the flight path of the object based on the non-uniformity correction.

2. The system of claim 1 wherein the infrared sensor is a long wave infrared uncooled sensor.

3. The system of claim 1 wherein the infrared modulator is configured to transmit translucent scattered infrared signals to the infrared sensor when activated by infrared signals.

4. The system of claim 1 wherein the infrared modulator transmits at least two translucent infrared signals of different intensities to the infrared sensor.

5. The system of claim 4 wherein the infrared modulator becomes transparent when activated.

6. The system of claim 5 wherein the guidance system further comprises:

a control circuit connected to the infrared modulator and the infrared sensor, the control system configured to

receive and modulate the at least two translucent infrared signals to produce a corrected image;

perform signal processing using the corrected image; and

provide an actuator signal to the guidance system wherein the flight path of the object is adjusted.

7. The system of claim 1 wherein the infrared modulator comprises smart glass.

8. The system of claim 7 wherein the mesomorphic material is a liquid crystal.

9. The system of claim 7 wherein the smart glass is a mesomorphic material or a suspended particle device.

10. A method for navigating an object comprising:

providing an infrared sensor having an optical path;

with an infrared modulator in the optical path of the infrared sensor, allowing the infrared sensor to perform, in situ, scene-based non-uniformity correction of a scene; and

adjusting a flight path of the object based on the non-uniformity correction.

11. The method of claim 10 wherein the object is contained within a guidance system.

12. The method of claim 11 wherein translucent scattered images of the scene are processed in the infrared sensor to produce intensity signals containing information useful for calculating non-uniform correction terms.

13. The method of claim 12 wherein a transparent image of the scene is processed in the infrared sensor to produce a scene intensity signal containing information which, in combination with the non-uniform correction terms, provides a spatially corrected uniform image.

14. A method of navigating an object comprising:

with an onboard spatial infrared modulator, applying a non-uniform correction to an infrared sensor, the non-uniform correction comprising;

with a video device,

obtaining a first video image of a first translucent scattered image of a scene having a target equivalent temperature, the scene containing a target blackbody object, a first equivalent blackbody object, and a second equivalent blackbody object, wherein the first equivalent blackbody object has a first intensity associated with a first equivalent temperature;

processing the first video image in the infrared sensor, wherein the infrared sensor provides a first intensity signal to a calculating device;

obtaining a second video image of a second translucent scattered image of the scene, wherein the second equivalent blackbody object has a second intensity associated with a second equivalent temperature;

processing the second video image in the infrared sensor, wherein the infrared sensor provides a second intensity signal to the calculating device;

calculating non-uniform correction terms from information in the first and second intensity signals;

with the infrared modulator operating in a transparent state, obtaining a third video image of the target blackbody object, the target blackbody object having a target blackbody intensity associated with the target equivalent temperature;

processing the third video image in the infrared sensor, wherein the infrared sensor provides a scene intensity signal to the calculating device; and

performing signal processing using the scene intensity signal and the non-uniform correction terms to produce a spatially corrected uniform image.

15. The method of claim 14 further comprising:

activating the onboard infrared modulator, wherein the onboard infrared modulator becomes transparent; and

providing an actuator signal to a guidance system in communication with the onboard infrared modulator.

16. The method of claim 14 wherein the infrared sensor is a focal plane array.

17. The method of claim 14 wherein the infrared modulator can switch from transmitting the second translucent scattered image to transmitting the subsequent transparent image in less than one (1) second.

18. The method of claim 14 wherein the infrared modulator can switch in 150 ms or less.

19. The method of claim 14 wherein the method further comprises transmitting an initial transparent image prior to transmitting the first translucent image, and the infrared modulator can switch from transmitting the initial transparent image to transmitting the first translucent image in 900 ms or less.

20. The method of claim 14 wherein the first, second and target equivalent temperatures comprise a scene effective temperature and the scene effective temperature ranges from 0°

C. to about 50°

C.

21. The method of claim 20 wherein the non-uniformity correction is performed at effective temperatures of between about 20°

C. and about 30°

C., such that calibration is provided over the entire scene effective temperature range.

22. A guided projectile comprising:

a housing;

an infrared modulator within the housing, wherein the infrared modulator is located between an infrared sensor and an infrared optical element, wherein the infrared modulator is configured to allow the infrared sensor to perform in situ scene-based non-uniformity correction; and

a guidance system within the casing, wherein the guidance system navigates the guided projectile based on the non-uniformity correction.

23. The guided projectile of claim 22 wherein the infrared optical element is an IR lens or a reflecting telescope.

24. The guided projectile of claim 22 wherein the infrared modulator becomes transparent when activated.

25. An infrared modulator comprising:

a non-uniform correction infrared (IR) spatial modulator located in an optical path of an IR sensor, wherein the IR spatial modulator is capable of transmitting and scattering variable intensities of IR radiation from a target imaged to the focal plane array (FPA) of a thermal IR sensor.

26. The infrared modulator of claim 25 wherein activation and deactivation of the IR modulator allows scene-based non-uniform correction to be performed.

27. The infrared modulator of claim 25 wherein the non-uniform correction can be applied in less than one second.

28. The infrared modulator of claim 25 comprising a liquid crystal device or a suspended particle device.