Single camera color and infrared polarimetric imaging

• US 8,411,146 B2
• Filed: 09/04/2009
• Issued: 04/02/2013
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Twede, David
• Primary Examiner(s): Dollinger, Tonia L
• Assistant Examiner(s): Murray, Daniel C
• Application Number:
  US12/554,681
• Publication Number:
  US 20110058038A1
• Time in Patent Office: 1,306 Days
• Field of Search: 348/148, 348/122, 348/135, 348/164, 250/225, 356/364
• US Class Current: 348/148
• CPC Class Codes: G01J 4/04 Polarimeters using electric detection means G01J4/02 takes precedence
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

A single aperture polarimetric color imaging system includes a color filter array including a plurality of RGB filter elements in a path of received radiation that includes color band and near IR light. A linear polarizer array includes a plurality of polarization filter elements that provide a plurality of different polarization orientations that are optically aligned with the RGB filter elements. A single common pixel array includes a plurality of photodetector pixels for transducing the color band or near IR light into electrical signals after processing by the color filter array and linear polarizer array. A band select switching device switches between selectively transmitting the near IR band and color band or color band including light. A signal processor is coupled to receive and process the electrical signals from the common pixel array and generates polarimetric image data from the near IR band light and color image data from the color band or color band including light.

Claims

1. A polarimetric color imaging system, comprising:

a single common aperture, wherein said system operates exclusively on received light collected through said single common aperture, said received light comprising color band light and near infrared (IR) band light;

a color filter array comprising a plurality of red (R), green (G), and blue (B) filter elements in a path of said received light;

a linear polarizer array comprising a plurality of polarization filter elements that provide a plurality of different polarization orientations optically aligned with respective ones of said R, G and B filter elements;

a single common pixel array comprising a plurality of photodetector pixels for transducing said color band light and said near IR band light after processing by said color filter array and said linear polarizer array into electrical signals, respective ones of said plurality photodetector pixels optically aligned with said plurality of R, G and B filter elements and said plurality of polarization filter elements;

a band select switching device in a path of said received light for switching between transmitting exclusively said near IR band light and said color band or color band comprising light, and

a signal processor coupled to receive and process said electrical signals exclusively from said single common pixel array, said signal processor generating color image data from said color band or said color band comprising light during first time intervals and polarimetric image data exclusively from said near IR band light during second time intervals that do not overlap with said first time intervals and color image data from said color band or said color band comprising light.

2. The polarimetric color imaging system of claim 1, wherein said pixel array, said color filter array and said linear polarizer array are in a stacked configuration.

3. The polarimetric color imaging system of claim 2, further comprising a substrate having a semiconductor surface, wherein said pixel array, said color filter array and said linear polarizer array are formed on said semiconductor surface, and said plurality of photodetector pixels comprise Complementary Metal-Oxide Semiconductor (CMOS) photodetector elements.

4. The polarimetric color imaging system of claim 1, wherein said red (R), green (G), and blue (B) filter elements of said color filter array are transmissive band pass filter elements which transmit individual wavebands of red (R), green (G), and blue (B) light, respectively.

5. The polarimetric color imaging system of claim 1, wherein said band select switching device comprises a mechanically rotating filter wheel.

6. The polarimetric color imaging system of claim 1, wherein said near IR band light includes a wavelength range from 750 nm to 1,000 nm.

7. The polarimetric color imaging system of claim 1, wherein said plurality of different polarization orientations comprise 0, 45, 90, and 135 degrees.

8. The polarimetric color imaging system of claim 1, wherein said plurality of different polarization orientations comprise 0, 60, and 120 degrees.

9. The polarimetric color imaging system of claim 1, wherein said signal processor generates fused overlays, said fused overlays combining said polarimetric image data and said color image data.

10. A vehicle having polarimetric color imaging, comprising:

an outer body, and

a polarimetric color imaging system mounted within said vehicle, said polarimetric imaging system comprising;

a single common aperture, wherein said system operates exclusively on received light collected through said single common aperture, said received radiation comprising color band signals and near infrared (IR) band light;

a color filter array comprising a plurality of red (R), green (G), and blue (B) filter elements in a path of said received light;

a linear polarizer array comprising a plurality of polarization filter elements that provide a plurality of different polarization orientations optically aligned with respective ones of said R, G and B filter elements;

a single common pixel array comprising a plurality of photodetector pixels for transducing said color band light and said near IR band light after processing by said color filter array and said linear polarizer array into electrical signals, respective ones of said plurality photodetector pixels optically aligned with said plurality of R, G and B filter elements and said plurality of polarization filter elements;

a band select switching device in a path of said received light for switching between transmitting exclusively said near IR band light and said color band or color band comprising light, and

a signal processor coupled to receive and process said electrical signals exclusively from said single common pixel array, said signal processor generating color image data from said color band or said color band comprising light during first time intervals and polarimetric image data exclusively from said near IR band light during second time intervals that do not overlap with said first time intervals and color image data from said color band or said color band comprising light.

11. The vehicle of claim 10, wherein said pixel array, said color filter array and said linear polarizer array are in a stacked configuration and wherein said red (R), green (G), and blue (B) filter elements of said color filter array are transmissive band pass filter elements which transmit individual wavebands of red (R), green (G), and blue (B) light, respectively.

12. The vehicle of claim 10, wherein said vehicle comprises a defense vehicle, further comprising an armament, and wherein said armament is aimed based at least in part on said polarimetric image data.

13. The vehicle of claim 12, further comprising a controller coupled to said signal processor operable to aim said armament based on said polarimetric image data.

14. A method of polarimetric color imaging, comprising:

receiving naturally occurring light emanating from at least one object through a single common aperture, said natural light comprising color band light and near infrared (IR) band light;

switching between exclusively transmitting said near IR band light and said color band light or color band comprising light as a transmitted signal;

array processing said transmitted signal comprising said color band light or said color band comprising light during first time intervals and exclusively said near IR band light during second time intervals that do not overlap with said first time intervals,

wherein said array processing of said transmitted signal comprises;

polarization filtering using a plurality of different polarization filter orientations that are spatially partitioned;

color bandpass filtering comprising spatially partitioned red (R), green (G), and blue (B) filtering, and

sensing said transmitted signal using a single common pixel array comprising a plurality of photodetector pixels following said polarization filtering and said color bandpass filtering to generate a plurality of electrical sensing signals, and

forming a polarimetric color image from said plurality of electrical sensing signals, a polarimetric portion of said polarimetric color image generated exclusively from said near IR band light obtained during said second time intervals and a color portion of said polarimetric color image generated from said color band or said color band comprising light obtained during said first time intervals.

15. The method of claim 14, wherein said switching is in a range from 30 to 60 Hz.

16. The method of claim 14, wherein said polarimetric color image comprises a fused overlay, said fused overlay combining polarimetric image data and color image data.

17. The method of claim 14, wherein said color band comprising light comprises said color band light and said near infrared IR band light.

18. The method of claim 17, wherein said forming said polarimetric color image further comprises subtraction of an intensity of said near IR band light obtained during said second time intervals to obtain said color portion of said of said polarimetric color image.

19. The method of claim 14, wherein said near IR band light includes a wavelength range from 750 nm to 1,000 nm.

20. The method of claim 14, wherein said red (R), green (G), and blue (B) filter elements of said color filter array are transmissive band pass filter elements which transmit individual wavebands of red (R), green (G), and blue (B) light, respectively.