Sensor assembly for imaging passive infrared and active LADAR and method for same

• US 6,323,941 B1
• Filed: 08/06/1999
• Issued: 11/27/2001
• Est. Priority Date: 08/06/1999
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Evans, Bruno J., Dodd, Mark Alan, Jenkins, Gary Kim
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US09/370,108
• Time in Patent Office: 844 Days
• Field of Search: 356/141.1, 356/4.01, 356/5.01, 356/376, 356/141.5, 250/339.02, 250/339.05, 250/342
• US Class Current: 356/4.01
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar

Abstract

A sensor assembly for imaging passive infrared (IR) scenes and active laser radar (LADAR) scenes and for generating multi-dimension image data sets, and a method for same. A two-dimensional semiconductor imager sensitive to both passive IR radiation and active LADAR radiation when used in conjunction with subsequent signal processing creates a two-dimension passive image data set and a three-dimension active image data set with common x and y coordinates. The passive image data set is collected substantially proximate in time with the active image data set. The two image data sets are combined to form a multi-dimension image data set with the surface of three-dimensional objects indicating heat emission. The sensor assembly applies to burst illumination LADARs operating at a variety of wavelengths and passive IR detection in the middle wavelength IR (MWIR) or long wavelength IR (LWIR).

Claims

1. A sensor assembly for detecting a scene which emits passive radiation and reflects active radiation, the sensor assembly comprising:

an imager for imaging the scene, said imager for producing a passive image signal based upon passive scene radiation and an active image signal based upon active scene radiation;

a passive signal channel for integrating the passive image signal for producing a passive image data set from said integrated passive image signal; and

an active signal channel for sampling the active image signal at predetermined times for producing an active image data set from said sampled active image signal, said active image data set comprising horizontal, vertical, and range data.

2. A sensor assembly in accordance with claim 1 wherein said passive image signal and said active image signal are produced simultaneously.

3. A sensor assembly in accordance with claim 1 wherein said imager comprises a linear array of imaging pixels.

4. A sensor assembly in accordance with claim 1 wherein said imager comprises an area array of imaging pixels.

5. A sensor assembly in accordance with claim 1 wherein said imager comprises a single semiconductor imager.

6. A sensor assembly in accordance with claim 5 wherein said single semiconductor imager comprises III-V semiconductor material.

7. A sensor assembly in accordance with claim 5 wherein said single semiconductor imager comprises II-VI semiconductor material.

8. A sensor assembly in accordance with claim 1 wherein said active scene radiation is imaged from a spatial subset of said scene relative to said imaged passive scene radiation.

9. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 3 microns and substantially 5 microns.

10. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 8 microns and substantially 12 microns.

11. A sensor assembly in accordance with claim 1 wherein said active scene radiation is reflected laser radiation.

12. A sensor assembly in accordance with claim 11 wherein said laser radiation has a wavelength of substantially 1.55 microns.

13. A sensor assembly in accordance with claim 11 wherein said laser radiation has a wavelength of substantially 10.6 microns.

14. A sensor assembly in accordance with claim 11 wherein said laser radiation has a wavelength of substantially 1.05 microns.

15. A sensor assembly in accordance with claim 11 wherein said laser radiation has a wavelength of substantially 4.1 microns.

16. A sensor assembly in accordance with claim 1 wherein said passive signal channel converts said passive image data set into a digital passive image data set.

17. A sensor assembly in accordance with claim 16 wherein said passive signal channel corrects said digital passive image data set for non-uniformity.

18. A sensor assembly in accordance with claim 1 wherein said active signal channel converts said active image data set into a digital active image data set.

19. A sensor assembly in accordance with claim 18 wherein said active signal channel corrects said digital active image data set for non-uniformity.

20. A sensor assembly in accordance with claim 1 wherein said active signal channel threshold detects said active image data set to remove noise data from said active image data set.

21. A sensor assembly in accordance with claim 1 wherein said sensor assembly images said scene at a rate corresponding to a video rate.

22. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 3 microns and substantially 5 microns, and said active image signal is based upon active scene radiation having a wavelength of substantially 1.55 microns.

23. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 3 microns and substantially 5 microns, and said active image signal is based upon active scene radiation having a wavelength of substantially 1.05 microns.

24. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 8 microns and substantially 12 microns, and said active image signal based upon active scene radiation having a wavelength of substantially 1.55 microns.

25. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 8 microns and substantially 12 microns, and said active image signal is based upon active scene radiation having a wavelength of substantially 1.05 microns.

26. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 8 microns and substantially 12 microns, and said active image signal based upon active scene radiation having a wavelength of substantially 4.1 microns.

27. A sensor assembly in accordance with claim 1 wherein said passive image signal is based upon passive scene radiation having a wavelength between substantially 8 microns and substantially 12 microns, and said active image signal is based upon active scene radiation having a wavelength of substantially 10.6 microns.

28. A sensor assembly for detecting a scene which emits passive radiation and reflects active radiation, the sensor assembly comprising:

an imager for imaging the scene, said imager for producing a passive image signal based upon passive scene radiation and an active image signal based upon active scene radiation;

a passive signal channel for integrating the passive image signal for producing a passive image data set from said integrated passive image signal;

an active signal channel for sampling the active image signal at predetermined times for producing an active image data set from said sampled active image signal, said active image data set comprising horizontal, vertical, and range data; and

a processor for receiving said produced passive image data set and said produced active image data set, and for producing a multi-dimension image data set which comprises horizontal, vertical, and range data and passive image signal data corresponding to said horizontal and vertical data.

29. A sensor assembly in accordance with claim 28 wherein said multi-dimension image data set further comprises active image signal data corresponding to said horizontal and vertical data.

30. A method for producing passive and active image data sets, the method comprising the steps of:

simultaneously detecting passive scene radiation for producing a passive image signal and active scene radiation for producing an active image signal with a single imager;

integrating said passive image signal for producing a passive image data set; and

sampling said active image signal at predetermined times for producing an active image data set, said active image data set comprising horizontal, vertical, and range data,

wherein said passive image data set and said active image data set have corresponding horizontal and vertical data.

31. A method for producing a multi-dimension image data set, the method comprising the steps of:

simultaneously detecting passive scene radiation for producing a passive image signal and active scene radiation for producing an active image signal with a single imager;

integrating said passive image signal for producing a passive image data set;

sampling said active image signal at predetermined times for producing an active image data set, said active image data set comprising horizontal, vertical, and range data; and

combining said passive image data set and said active image data set for producing a multi-dimension data set,

wherein said passive image data set and said active image data set have corresponding horizontal and vertical data.

32. An imaging system for producing an image of a scene by use of radiation in a first band and radiation in a second band, comprising:

a laser generator for producing pulses of a laser beam that illuminates at least a substantial portion of said scene, said laser beam having a wavelength in said first band and said pulses having a timed sequence;

an imager for producing image data of said scene by receiving passive radiation, which has a wavelength in said second band, from said scene and by receiving reflections of said laser beam from said scene wherein said imager produces a first image signal corresponding to detection of said passive radiation and a second image signal corresponding to detection of said active radiation, which comprises said reflections of said laser beam;

a passive image channel for producing a passive radiation image data set from said first image signal;

an active image channel for producing an active radiation image data set from said second image signal, said active image data set comprising horizontal, vertical, and range data;

said passive radiation image data set defining a passive radiation image of said scene and said active radiation image data set defining an active radiation image of said scene and wherein said passive radiation image and said active radiation image are horizontally and vertically registered with each other; and

a processor for combining registered data points of said passive radiation image data set and said active radiation image data set and utilizing data based on said timed sequence of said laser pulses to produce a composite image data set which comprises said image of said scene.

33. An imaging system as recited in claim 32 including a digital data store for receiving and storing therein said passive radiation image data set, said active radiation image data set and said data based on said timed sequence of said laser pulses, wherein said data store is connected to provide data stored therein to said processor.