CODED APERTURE IMAGING SYSTEM

• US 20090095912A1
• Filed: 05/23/2006
• Published: 04/16/2009
• Est. Priority Date: 05/23/2005
• Status: Active Grant

• Current Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Slinger, Christopher W., Lewis, Keith L.
• Granted Patent: US 7,888,626 B2
• Time in Patent Office: Days
• US Class Current: 250/363.06
• CPC Class Codes: G01T 1/295 using coded aperture devices, e.g. Fresnel zone plates handling of radiation of particles, e.g. using diaphragms, collimators, diffraction G21K1/00
• CPC Class Codes: G02B 2207/129 Coded aperture imaging
• CPC Class Codes: G02B 27/00 Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
• CPC Class Codes: G06T 1/0007 Image acquisition
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/58 Means for changing the camera field of view without moving the camera body, e.g. nutating or panning of optics or image sensors
• CPC Class Codes: H04N 23/951 by using two or more images to influence resolution, frame rate or aspect ratio
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• 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

This invention relates to coded aperture imaging apparatus and methods. In one aspect a coded aperture imager has at least one detector array and a reconfigurable coded aperture mask means. A reconfigurable coded aperture mask means can display various coded aperture masks to provide imaging across different fields of view and/or with different resolution without requiring any moving parts or bulky optical components. More than one detector array can be used to provide large area imaging without requiring seamless tiling and this represents another aspect of the invention. The present invention also relates to the use of coded aperture imaging in the visible, ultraviolet or infrared wavebands. The use of coded aperture imaging for imaging through a curved optical element is taught as the image decoding can automatically remove any aberrations introduced by the curved element.

Claims

1. A coded aperture imaging system comprising a detector array and a coded aperture mask means wherein the coded aperture mask means is reconfigurable.

2. An imaging system as claimed in claim 1 wherein the coded aperture mask means is reconfigurable to provide coded aperture masks having different fields of view.

3. An imaging system as claimed in claim 2 wherein only part of the coded aperture mask comprises a coded aperture array and wherein the position of the coded aperture array in the mask defines the field of view.

4. An imaging system as claimed in claim 1 wherein the coded aperture mask means is reconfigurable to provide coded aperture masks having different resolutions.

5. An imaging system as claimed in claim 1 wherein the coded aperture mask means is reconfigurable to provide coded aperture masks having different coded aperture arrays.

6. An imaging system as claimed in claim 1 wherein the reconfigurable coded aperture mask means comprises a controller adapted to write at least one coded aperture mask to the coded aperture mask means.

7. An imaging system according to claim 6 wherein the controller is pre-programmed with a plurality of different coded aperture masks.

8. An imaging system as claimed in claim 1 wherein the coded aperture mask means is non-planar.

9. An imaging system as claimed in claim 1 wherein the coded aperture mask means is reconfigurable in less than 150 ms, or less than 100 ms, or less than 50 ms, or less than 15 ms, or less than 10 ms or less than 5 ms.

10. An imaging system as claimed in claim 1 wherein the coded aperture mask means comprises a spatial light modulator.

11. An imaging system as claimed in claim 10 wherein the spatial light modulator is bistable.

12. An imaging system as claimed in claim 10 wherein the spatial light modulator is a liquid crystal device.

13. An imaging system as claimed in claim 1 comprising a processor adapted to decode the output of the detector array to provide an image.

14. An imaging system as claimed in claim 13 wherein the processor is adapted to apply a variety of decoding algorithms to decode the output of the detector array.

15. An imaging system as claimed in claim 13 wherein the processor combines multiple frames of data from the detector array, each frame acquired with a different coded aperture mask

16. An imaging system as claimed in claim 1 comprising a transmitter/recorder for transmitting/recording the undecoded output of the detector array.

17. An imaging system as claimed in claim 16 wherein the reconfigurable coded aperture array means is adapted to vary the coded aperture mask displayed to vary the image encryption.

18. A visible band imaging system comprising a detector array and a visible band coded aperture mask means.

19-20. -20. (canceled)

21. A method of imaging comprising the steps of arranging a detector array to view a scene through a reconfigurable coded aperture array means and writing a coded aperture mask to the coded aperture mask means.

22. A method of imaging as claimed in claim 21 writing a first coded aperture mask to the coded aperture mask means and subsequently writing a second coded aperture mask to the coded aperture mask means.

23. A method of imaging as claimed in claim 22 wherein the first and second coded aperture masks have different fields of view and/or resolution.

24. A method of imaging as claimed in claim 21 wherein the method comprises the step of decoding the output of the detector array to provide an image.

25. A method as claimed in claim 24 wherein the step of decoding comprises applying one or more of a deconvolution algorithm, a cross-correlation algorithm and an iterative solution search.

26. A method as claimed in claim 22 wherein the method involves combining data acquired using a plurality of different coded aperture masks in decoding the image.

27. An imaging system comprising a coded aperture imager arranged to image through a non-planar element.

28. An imaging system as claimed in claim 27 wherein the coded aperture imager comprises at least one detector and a coded aperture mask means.

29. An imaging system as claimed in claim 28 wherein the coded aperture mask means is reconfigurable.

30. An imaging system as claimed in claim 27 wherein the non-planar element forms part of the external surface of a platform.

31. An imaging system as claimed in claim 27 wherein the non-planar element has an aerodynamic shape.

34. A coded aperture imaging system as claimed in claim 29 wherein the active area of at least one detector array is not coterminous with the active area of a neighbouring detector array.

32. A coded aperture imaging system having a plurality of detector arrays arranged to receive radiation from a scene through a coded aperture mask.

33. A coded aperture imaging system as claimed in claim 32 wherein each detector array has an active detector area for receiving radiation and a non-active peripheral area.