Divided-aperture infra-red spectral imaging system for chemical detection

• US 9,625,318 B2
• Filed: 11/17/2014
• Issued: 04/18/2017
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: Rebellion Photonics, Inc. (Honeywell International Inc.)
• Original Assignee: Rebellion Photonics, Inc. (Honeywell International Inc.)
• Inventors: Kester, Robert T., Hagen, Nathan A.
• Primary Examiner(s): Bryant, Casey
• Application Number:
  US14/543,692
• Publication Number:
  US 20150069239A1
• Time in Patent Office: 883 Days
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/0232 using shutters
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G06T 7/254 involving subtraction of images

Abstract

A divided-aperture infrared spectral imaging (DAISI) system that is structured to provide identification of target chemical content in a single imaging shot based on spectrally-multiplexed operation. The system is devoid of spectral scanning acquisition of infrared (IR) spectral signatures of target content with an IR detector and does not require content.

Claims

1. An infrared (IR) imaging system for determining a concentration of a target species in an object, the imaging system comprising:

an optical system including an optical focal plane array (FPA) unit, the optical system comprising a plurality of optical channels defined by components of the optical system that are arranged in a two-dimensional array, said plurality of optical channels being spatially and spectrally different from one another and configured to direct IR radiation from the object towards the optical FPA unit;

a first movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from the object, wherein a portion of the movable shutter is maintained at a first temperature and another portion of the movable shutter is maintained at a second temperature; and

a processor configured to acquire multispectral optical data representing said target species from the received IR radiation in a single occurrence of data acquisition.

2. The system of claim 1, wherein the FPA unit does not require a cooler to cool during normal operation.

3. The system of claim 1, wherein the IR radiation comprises wavelengths between about 1 micron and about 20 microns.

4. The system of claim 1, wherein the processor is configured to map an overall image datacube representing a spatial distribution of concentrations c of the target species.

5. The system of claim 1, wherein the system is configured to identify target species in a gas cloud.

6. The system of claim 1, further comprising a plurality of spectral filters, each filter positioned in a respective one of said plurality of optical channels.

7. The system of claim 6, wherein the spectral filters comprise at least one long pass (LP) filter.

8. The system of claim 6, wherein the spectral filters comprise at least one short pass (SP) filter.

9. The system of claim 6, further comprising a plurality of reimaging lenses, each reimaging lens positioned to transmit a portion of the IR radiation transmitted through a respective one of said spectral filters towards the optical FPA unit.

10. The system of claim 1, further comprising an optical aperture that circumscribes said plurality of optical channels.

11. The system of claim 1, wherein the processor is configured to calibrate the FPA unit based on the first and the second temperature.

12. A method for operating an infrared (IR) imaging system, comprising:

receiving IR radiation from an object along a plurality of spatially and spectrally different channels formed by a plurality of focal plane arrays of an optical focal plane array (FPA) unit, the plurality of focal plane arrays arranged in a two-dimensional array comprising at least two rows and two columns; and

removably positioning a first and a second movable shutter in front of the optical system to block IR radiation incident onto the optical system from the object, wherein the first movable shutter is maintained at a first temperature and the second movable shutter is maintained at a second temperature.

13. The method of claim 12, wherein the FPA unit does not require a cooler to provide cooling during normal operation.

14. The method of claim 12, wherein at least some of the plurality of spatially and spectrally different channels comprise spectral filters.

15. The method of claim 14, wherein the spectral filters includes one of a longpass optical filter or a shortpass optical filter.

16. The method of claim 12, further comprising acquiring multispectral optical data representing the object from the received IR radiation in a single occurrence of data acquisition with a programmable processor.

17. The method of claim 12, configured to identify target species in a gas cloud.

18. The method of claim 12, further comprising calibrating the FPA unit based on the first and the second temperature.

19. An infrared (IR) imaging system for determining a concentration of a target species in an object, the imaging system comprising:

an optical system including an optical focal plane array (FPA) unit, the optical focal plane array (FPA) unit comprising a plurality of focal plane arrays arranged in a two-dimensional array to form a plurality of spatially different channels arranged in a two-dimensional array that are configured to receive IR radiation from the object, wherein the two-dimensional array comprises at least two rows and two columns of focal plane arrays;

a first and a second movable shutter configured to be removably positioned to block IR radiation incident onto the optical system from the object, wherein the first movable shutter is maintained at a first temperature and the second movable shutter is maintained at a second temperature for calibration; and

a processor configured to acquire multispectral optical data representing said target species from the received IR radiation.

20. The system of claim 19, wherein the FPA unit does not require a cooler to provide cooling during normal operation.

21. The system of claim 19, wherein the IR radiation comprises wavelengths between about 1 micron and about 20 microns.

22. The system of claim 19, wherein the plurality of channels are spectrally distinct from each other.

23. The system of claim 19, wherein the system is configured to identify target species in a gas cloud.

24. The system of claim 19, further comprising a plurality of spectral filters, each filter positioned in a respective one of said plurality of channels.

25. The system of claim 24, wherein the spectral filters comprise at least one long pass (LP) filter.

26. The system of claim 24, wherein the spectral filters comprise at least one short pass (SP) filter.

27. The system of claim 19, wherein the processor is configured to acquire multispectral optical data in a single occurrence of data acquisition.

28. The system of claim 19, wherein the system is configured to identify target species in a gas cloud.

29. The system of claim 19, wherein the processor is configured to calibrate the FPA unit based on the first and the second temperature.