Infrared laser illuminated imaging systems and methods

• US 20070221849A1
• Filed: 07/12/2005
• Published: 09/27/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Roberts, David, King, Carl, Tabirian, Anna, Stanley, Douglas, Thompson, Arthur
• Granted Patent: US 7,541,588 B2
• Time in Patent Office: Days
• US Class Current: 250/341.100
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/486 Receivers

Abstract

Systems and methods for long range recognition and identification of objects and targets, and, more particularly, to long range imaging systems that include the use of mid-wave infrared laser illumination technology are provided. In particular, mid-wave infrared laser illuminated imaging systems and methods are disclosed for addressing, among other things, the problems associated with long range, day or night observations of targets through various obscurants (e.g., fog, haze, rain, smoke). Such systems may be configured to operate in either a single, active illumination mode or in a dual, active/passive mode.

Claims

1. A system for observing an object, the system comprising:

a laser for illuminating the object with a signal from within a mid-wave infrared spectral region;

a mid-wave imaging camera for collecting imaging data of the object in the mid-wave infrared spectral region; and

a controller for coordinating operations associated with one or more of the laser and the imaging camera.

2. The system of claim 1, wherein said laser and said camera are configured to operate is a mid-infrared 3 to 5 micron wavelength range.

3. The system of claim 1, wherein said laser is at least one of a pulsed Ho:

BYF laser, or a pulsed Ho;

YLF laser

4. The system of claim 1, wherein said laser is at least one of a frequency doubled CO₂ laser, a Nd:

YAG laser in combination with a nonlinear crystal for shifting the wavelength of the output signal or a laser in combination with a nonlinear element for shifting the wavelength of the output signal into the mid-wave infrared spectral range.

5. The system of claim 1, wherein said mid-wave imaging camera comprises a gated camera for capturing imaging data only during a time interval when signals emitted by said laser and reflected by the object are incident upon said camera.

6. The system of claim 5, wherein said camera is a gated InSb or HgCdTe camera having a focal plane array, with a readout integrated circuit capable of selecting and gating out multiple time intervals with a single laser pulse.

7. The system of claim 1 further comprising a range receiver for determining a distance to the object.

8. The system of claim 7, wherein said range receiver comprises a mid-wave infrared detector configured to measure a time-of-flight of one or more pulses occurring prior to the one or more pulses used for collecting the imaging data.

9. The system of claim 1, wherein said controller is capable of coordinating the operations of the imaging camera to capture both imaging data that is responsive to illumination of the object by the signals provided by said laser in an active mode of operation and imaging data associated with the object that is independent of illumination of the object by the signals provided by said laser in a passive mode of operation.

10. The system of claim 9 further comprising a display device for displaying an image of the object.

11. The system of claim 10 wherein said display device is capable of displaying the image of the object that is concurrently comprised of imagery data collected while in both the active and passive modes of operation.

12. The system of claim 11 wherein said display device is capable of visually distinguishing those features of the image that are based on imagery data collected in the active mode of operation from those features of the image that are based on imagery data collected in the passive mode of operation.

13. A method of observing an object comprising:

illuminating the object with a signal within a mid-wave infrared spectral region;

collecting imaging data of the object in the mid-wave infrared spectral region; and

generating an image of the object based on the collected imaging data.

14. The method of claim 13, wherein illuminating the object comprises illuminating the object with a signal having a wavelength in a mid-infrared 3 to 5 micron wavelength range, and wherein collecting imaging data comprises collecting imaging data in the mid-infrared 3 to 5 micron wavelength range.

15. The method of claim 13, wherein collecting imaging data comprises capturing imaging data only during a time interval when signals in the mid-wave infrared spectral region are returning following reflection by the object.

16. The method of claim 13, further comprising determining a distance to the object by measuring a time-of-flight of one or more pulses occurring prior to the one or more pulses used for collecting the imaging data.

17. The method of claim 13, further comprising coordinating the collection of imagery data to collect both imaging data that is responsive to illumination of the object by the signals in the mid-wave infrared spectral region in an active mode of operation and imaging data associated with the object that is independent of illumination of the object by the signals in the mid-wave infrared spectral region in a passive mode of operation.

18. The method of claim 17 further comprising displaying the generated image of the object.

19. The method of claim 18 wherein displaying the generated image comprises displaying an image of the object that is concurrently comprised of imagery data collected while in both the active and passive modes of operation.

20. The method of claim 19 wherein displaying the image comprises visually distinguishing those features of the image that are based on imagery data collected in the active mode of operation from those features of the image that are based on imagery data collected in the passive mode of operation.

21. A system for observing an object, the system comprising:

a laser for illuminating the object with a signal from within a short-wave infrared spectral region; and

a single camera for collecting imaging data of the object both in the short-wave infrared spectral region and also in the mid-wave infrared spectral region; and

a controller for coordinating operations associated with one or more of the laser and the camera.

22. The system of claim 21, wherein said camera is configured to operate in both a shortwave infrared 1.0 to 2.5 micron wavelength range and a mid-infrared 3 to 5 micron wavelength range.

23. The system of claim 21, wherein said camera comprises a gated camera for capturing imaging data only during a time interval when signals emitted by said laser and reflected by the object are incident upon said camera.

24. The system of claim 21, wherein said controller is capable of coordinating the operations of said camera to capture both imaging data that is responsive to illumination of the object by the signals provided by said laser in an active mode of operation and imaging data associated with the object that is independent of illumination of the object by the signals provided by said laser in a passive mode of operation.

25. The system of claim 24 further comprising a display device for displaying an image of the object, wherein said display device is capable of displaying the image of the object that is concurrently comprised of imagery data collected while in both the active and passive modes of operation.

26. The system of claim 25 wherein said display device is capable of visually distinguishing those features of the image that are based on imagery data collected in the active mode of operation from those features of the image that are based on imagery data collected in the passive mode of operation.

27. A method of observing an object comprising:

illuminating the object with a signal within a shortwave infrared spectral region;

collecting imaging data of the object with a single camera both in the shortwave infrared spectral region in response to the illumination of the object and in the mid-wave infrared spectral region; and

generating an image of the object based on the collected imaging data.

28. The method of claim 27, wherein illuminating the object comprises illuminating the object with a signal having a wavelength in a shortwave infrared 1.0 to 2.5 micron wavelength range, and wherein collecting imaging data comprises collecting imaging data in both the shortwave infrared 1.0 to 2.5 micron wavelength range and the mid-infrared 3 to 5 micron wavelength range.

29. The method of claim 27, wherein collecting imaging data comprises capturing imaging data only during a time interval when signals in the mid-wave infrared spectral region are returning following reflection by the object.

30. The method of claim 27, further comprising coordinating the collection of imagery data to collect both imaging data that is responsive to illumination of the object by the signals in the shortwave infrared spectral region in an active mode of operation and imaging data associated with the object that is independent of illumination of the object by the signals in the mid-wave infrared spectral region in a passive mode of operation.

31. The method of claim 30 further comprising displaying the generated image of the object, wherein displaying the generated image comprises displaying an image of the object that is concurrently comprised of imagery data collected while in both the active and passive modes of operation.

32. The method of claim 31 wherein displaying the image comprises visually distinguishing those features of the image that are based on imagery data collected in the active mode of operation from those features of the image that are based on imagery data collected in the passive mode of operation.