Hybrid LADAR with co-planar scanning and imaging field-of-view

• US 10,571,574 B1
• Filed: 02/14/2017
• Issued: 02/25/2020
• Est. Priority Date: 02/15/2016
• Status: Active Grant

• Current Assignee: Red Creamery LLC
• Original Assignee: Red Creamery LLC
• Inventors: Yavid, Dmitriy
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US15/432,105
• Time in Patent Office: 1,106 Days
• Field of Search: 356 501
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487

Abstract

A laser radar includes: a laser, an optical transmission system, a 1-dimensional array of photo-detectors, an optical reception system, and an electronic control system. The laser emits a wavelength of light, and the optical transmission system shapes the light into a beam, and scans the beam along a fan of transmission light paths toward a target. The photo-detectors are capable of time-of-arrival measurements and are sensitive to the wavelength of light. The optical reception system collects the laser light reflected from the target along a fan of reception light paths. The electronic control system synchronizes the scan of the beam with a respective time-of-arrival measurement from each of the photo-detectors, and analyzes the time-of-arrival measurements. The system is configured for all of the transmission light paths and all of the reception light paths to lie in one plane, with all of the reception light paths intersecting with at least one of the transmission light paths.

Claims

1. A laser radar (LADAR) comprising:

a laser configured to emit a wavelength of light;

an optical transmission system configured to shape the light emitted by said laser into a beam, and to scan said beam along a fan of transmission light paths toward a target;

a 1-dimensional array of photo-detectors, capable of time-of-arrival measurements and sensitive to said wavelength of light emitted by said laser;

an optical reception system configured to collect said laser light reflected from the target onto said photo-detectors of said array along a fan of reception light paths;

an electronic control system configured to synchronize said scan of said beam with a respective time-of-arrival measurement from each said photo-detector, and to analyze said time-of-arrival measurements;

wherein all of said transmission light paths and all of said reception light paths lie in one plane;

wherein every said reception light path intersects with at least one of said transmission light paths;

where the laser is pulsed at least once while the transmission path of said scan of said beam intersects the reception paths from each detector in the array;

where each pulse of said laser is timed to coincide with a center of the laser beam being coincident with a center of a field of view (FOV) of one of said photo-detectors; and

where said timed laser pulses are automatically adjusted based on said analyzed time-of-arrival measurements from the array of photo-detectors.

2. The LADAR of claim 1, where an angle of a field of view (FOV) of each of said photo-detectors in the array in the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

3. The LADAR of claim 1, where an angle of a field of view (FOV) of each of said photo-detectors in the array in a direction perpendicular to the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

4. The LADAR of claim 1 where an angle of a field of view (FOV) of each of said photo-detectors in the direction of the array is the same as a total scan angle of said transmission system.

5. The LADAR of claim 1, where the laser is continuously on while the transmission path of said scan of said beam intersects the reception paths from all the detectors in the array.

6. The LADAR of claim 1, wherein said LADAR is placed on an aerial platform moving in the direction perpendicular to said plane containing the light paths of said transmission system.

7. The LADAR of claim 1, with a scanning mirror positioned in an optical path of the scanned laser beam, with an axis of rotation parallel to said plane containing the light paths of said transmission system.

8. The LADAR of claim 1 mounted on a rotational stage with an axis of rotation being parallel to said plane containing the light paths of said transmission system.

9. The LADAR of claim 1 where the photodetectors are Avalanche Photo Diodes (APD).

10. The LADAR of claim 9 where the photodetectors are Geiger-mode Avalanche Photo Diodes (APD).

11. The LADAR of claim 1 where the photodetectors are equipped with individual time counters configured to record a time of arrival of a first photon after a reset.

12. The LADAR of claim 1 where the photodetectors are equipped with multiple time counters configured to record a time of the arrival of multiple light pulses reflected from multiple objects on the path of the laser beam.

13. The LADAR of claim 1 wherein said transmission optical system comprises a mirror configured to produce said scan of said laser beam;

and where the mirror is a mechanical resonant mirror.

14. The LADAR of claim 13 further comprising a system clock;

and where a frequency of said system clock is an integer multiple of a frequency of said scan of said mirror.

15. The LADAR of claim 14 where the system clock is phase-locked to oscillations of said mechanical resonant mirror.

16. The LADAR of claim 1 where said optical transmission system comprises a non-mechanical beam scanner (NMBS) configured for said scan of said laser beam.

17. The LADAR of claim 1 where said optical transmission system is configured to form a scan line on a surface of a diffractive element, and for said scan line to be imaged onto the target through an optical element.

18. The LADAR of claim 1 wherein said optical system comprises a mirror configured to produce said scan of said laser beam;

and where said optical system is configured for the laser beam to be focused on the mirror in a direction parallel to a scan axis of the mirror, and to then be re-collimated by a cylindrical lens.

19. The LADAR of claim 1 where a height of each pixel exceeds a pitch of each pixel.

20. The LADAR of claim 1 where each pixel of the laser light collected by said photodetectors is subdivided into several sub-pixels, and a response from each of the subpixels is separately amplified and analyzed.

21. The LADAR of claim 1 wherein said optical reception system comprises a micro-lens positioned in front of every detector.

22. The LADAR of claim 1 where each of said photo-detectors is armed after receipt of a first reflected pulse of light before being able to receive a next reflected light pulse, and wherein said photo-detectors are armed sequentially with a delay corresponding to a time for said scanned spot to sequentially move to each said center of said FOV of each said photo-detector.

23. The LADAR of claim 1 where a frequency of said scan exceeds 10 kHz.

24. The LADAR of claim 1 where a frequency of said scan exceeds 30 kHz.

25. The LADAR of claim 1 where each individual photo-detector is illuminated for no more than 60 nanoseconds during each scan.

26. The LADAR of claim 1 where each photo-detector is illuminated for no more than 20 nanoseconds during one scan.

27. The LADAR of claim 1 where the laser is a diode laser.

28. The LADAR of claim 1 where the laser emits eye-sate light with said wavelength exceeding 1400 nm.

29. A laser radar (LADAR) comprising:

a laser configured to emit a wavelength of light;

an optical transmission system configured to shape the light emitted by said laser into a beam, and to scan said beam along a fan of transmission light paths toward a target;

a 1-dimensional array of photo-detectors, capable of time-of-arrival measurements and sensitive to said wavelength of light emitted by said laser;

an optical reception system configured to collect said laser light reflected from the target onto said photo-detectors of said array along a fan of reception light paths;

an electronic control system configured to synchronize said scan of said beam with a respective time-of-arrival measurement from each said photo-detector, and to analyze said time-of-arrival measurements;

wherein all of said transmission light paths and all of said reception light paths lie in one plane;

wherein every said reception light path intersects with at least one of said transmission light paths; and

where the photodetectors are equipped with multiple time counters configured to record a time of the arrival of multiple light pulses reflected from multiple objects on the path of the laser beam.

30. The LADAR of claim 29, where an angle of a field of view (FOV) of each of said photo-detectors in the array in the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

31. The LADAR of claim 29, where an angle of a field of view (FOV) of each of said photo-detectors in the array in a direction perpendicular to the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

32. The LADAR of claim 29, where an angle of a field of view (FOV) of each of said photo-detectors in the direction of the array is the same as a total scan angle of said transmission system.

33. The LADAR of claim 29, where the laser is continuously on while the transmission path of said scan of said beam intersects the reception paths from all the detectors in the array.

34. The LADAR of claim 29, where the laser is pulsed at least once while the transmission path of said scan of said beam intersects the reception paths from each detector in the array.

35. The LADAR of claim 34, where each pulse of said laser is timed to coincide with a center of the laser beam being coincident with a center of a field of view (FOV) of one of said photo-detectors.

36. The LADAR of claim 35, where said timed laser pulses are automatically adjusted based on said analyzed time-of-arrival measurements from the array of photo-detectors.

37. The LADAR of claim 29, wherein said LADAR is placed on an aerial platform moving in the direction perpendicular to said plane containing the light paths of said transmission system.

38. The LADAR of claim 29, with a scanning mirror positioned in an optical path of the scanned laser beam, with an axis of rotation parallel to said plane containing the light paths of said transmission system.

39. The LADAR of claim 29 mounted on a rotational stage with an axis of rotation being parallel to said plane containing the light paths of said transmission system.

40. The LADAR of claim 29 where the photodetectors are Avalanche Photo Diodes (APD).

41. The LADAR of claim 40 where the photodetectors are Geiger-mode Avalanche Photo Diodes (APD).

42. The LADAR of claim 29 where the photodetectors are equipped with individual time counters configured to record a time of arrival of a first photon after a reset.

43. The LADAR of claim 29 wherein said transmission optical system comprises a mirror configured to produce said scan of said laser beam;

and where the mirror is a mechanical resonant mirror.

44. The LADAR of claim 43 further comprising a system clock;

and where a frequency of said system clock is an integer multiple of a frequency of said scan of said mirror.

45. The LADAR of claim 44 where the system clock is phase-locked to oscillations of said mechanical resonant mirror.

46. The LADAR of claim 29 where said optical transmission system comprises a non-mechanical beam scanner (NMBS) configured for said scan of said laser beam.

47. The LADAR of claim 29 where said optical transmission system is configured to form a scan line on a surface of a diffractive element, and for said scan line to be imaged onto the target through an optical element.

48. The LADAR of claim 29 wherein said optical system comprises a mirror configured to produce said scan of said laser beam;

and where said optical system is configured for the laser beam to be focused on the mirror in a direction parallel to a scan axis of the mirror, and to then be re-collimated by a cylindrical lens.

49. The LADAR of claim 29 where a height of each pixel exceeds a pitch of each pixel.

50. The LADAR of claim 29 where each pixel of the laser light collected by said photodetectors is subdivided into several sub-pixels, and a response from each of the subpixels is separately amplified and analyzed.

51. The LADAR of claim 29 wherein said optical reception system comprises a micro-lens positioned in front of every detector.

52. The LADAR of claim 36 where each of said photo-detectors is armed after receipt of a first reflected pulse of light before being able to receive a next reflected light pulse, and wherein said photo-detectors are armed sequentially with a delay corresponding to a time for said scanned spot to sequentially move to each said center of said FOV of each said photo-detector.

53. The LADAR of claim 29 where a frequency of said scan exceeds 10 kHz.

54. The LADAR of claim 29 where a frequency of said scan exceeds 30 kHz.

55. The LADAR of claim 29 where each individual photo-detector is illuminated for no more than 60 nanoseconds during each scan.

56. The LADAR of claim 29 where each photo-detector is illuminated for no more than 20 nanoseconds during one scan.

57. The LADAR of claim 29 where the laser is a diode laser.

58. The LADAR of claim 29 where the laser emits eye-safe light with said wavelength exceeding 1400 nm.

59. A laser radar (LADAR) comprising:

a laser configured to emit a wavelength of light;

an optical transmission system configured to shape the light emitted by said laser into a beam, and to scan said beam along a fan of transmission light paths toward a target;

a 1-dimensional array of photo-detectors, capable of time-of-arrival measurements and sensitive to said wavelength of light emitted by said laser;

an optical reception system configured to collect said laser light reflected from the target onto said photo-detectors of said array along a fan of reception light paths;

an electronic control system configured to synchronize said scan of said beam with a respective time-of-arrival measurement from each said photo-detector, and to analyze said time-of-arrival measurements;

wherein all of said transmission light paths and all of said reception light paths lie in one plane;

wherein every said reception light path intersects with at least one of said transmission light paths; and

where each pixel of the laser light collected by said photodetectors is subdivided into several sub-pixels, and a response from each of the subpixels is separately amplified and analyzed.

60. The LADAR of claim 59, where an angle of a field of view (FOV) of each of said photo-detectors in the array in the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

61. The LADAR of claim 59, where an angle of a field of view (FOV) of each of said photo-detectors in the array in a direction perpendicular to the direction of the array is the same as a divergence angle of said planar fan of transmission light paths in the same direction.

62. The LADAR of claim 59, where an angle of a field of view (FOV) of each of said photo-detectors in the direction of the array is the same as a total scan angle of said transmission system.

63. The LADAR of claim 59, where the laser is continuously on while the transmission path of said scan of said beam intersects the reception paths from all the detectors in the array.

64. The LADAR of claim 59, where the laser is pulsed at least once while the transmission path of said scan of said beam intersects the reception paths from each detector in the array.

65. The LADAR of claim 64, where each pulse of said laser is timed to coincide with a center of the laser beam being coincident with a center of a field of view (FOV) of one of said photo-detectors.

66. The LADAR of claim 65, where said timed laser pulses are automatically adjusted based on said analyzed time-of-arrival measurements from the array of photo-detectors.

67. The LADAR of claim 59, wherein said LADAR is placed on an aerial platform moving in the direction perpendicular to said plane containing the light paths of said transmission system.

68. The LADAR of claim 59, with a scanning mirror positioned in an optical path of the scanned laser beam, with an axis of rotation parallel to said plane containing the light paths of said transmission system.

69. The LADAR of claim 59 mounted on a rotational stage with an axis of rotation being parallel to said plane containing the light paths of said transmission system.

70. The LADAR of claim 59 where the photodetectors are Avalanche Photo Diodes (APD).

71. The LADAR of claim 70 where the photodetectors are Geiger-mode Avalanche Photo Diodes (APD).

72. The LADAR of claim 59 where the photodetectors are equipped with individual time counters configured to record a time of arrival of a first photon after a reset.

73. The LADAR of claim 59 where the photodetectors are equipped with multiple time counters configured to record a time of the arrival of multiple light pulses reflected from multiple objects on the path of the laser beam.

74. The LADAR of claim 59 wherein said transmission optical system comprises a mirror configured to produce said scan of said laser beam;

and where the mirror is a mechanical resonant mirror.

75. The LADAR of claim 74 further comprising a system clock;

and where a frequency of said system clock is an integer multiple of a frequency of said scan of said mirror.

76. The LADAR of claim 75 where the system clock is phase-locked to oscillations of said mechanical resonant mirror.

77. The LADAR of claim 59 where said optical transmission system comprises a non-mechanical beam scanner (NMBS) configured for said scan of said laser beam.

78. The LADAR of claim 59 where said optical transmission system is configured to form a scan line on a surface of a diffractive element, and for said scan line to be imaged onto the target through an optical element.

79. The LADAR of claim 59 wherein said optical system comprises a mirror configured to produce said scan of said laser beam;

and where said optical system is configured for the laser beam to be focused on the mirror in a direction parallel to a scan axis of the mirror, and to then be re-collimated by a cylindrical lens.

80. The LADAR of claim 59 where a height of each pixel exceeds a pitch of each pixel.

81. The LADAR of claim 59 wherein said optical reception system comprises a micro-lens positioned in front of every detector.

82. The LADAR of claim 66 where each of said photo-detectors is armed after receipt of a first reflected pulse of light before being able to receive a next reflected light pulse, and wherein said photo-detectors are armed sequentially with a delay corresponding to a time for said scanned spot to sequentially move to each said center of said FOV of each said photo-detector.

83. The LADAR of claim 59 where a frequency of said scan exceeds 10 kHz.

84. The LADAR of claim 59 where a frequency of said scan exceeds 30 kHz.

85. The LADAR of claim 59 where each individual photo-detector is illuminated for no more than 60 nanoseconds during each scan.

86. The LADAR of claim 59 where each photo-detector is illuminated for no more than 20 nanoseconds during one scan.

87. The LADAR of claim 59 where the laser is a diode laser.

88. The LADAR of claim 59 where the laser emits eye-safe light with said wavelength exceeding 1400 nm.