3D imaging laser radar

• US 6,133,989 A
• Filed: 06/19/1996
• Issued: 10/17/2000
• Est. Priority Date: 02/09/1993
• Status: Expired due to Fees

• Current Assignee: Continental Autonomous Mobility US LLC (Continental AG)
• Original Assignee: Advanced Scientific Concepts, Inc.
• Inventors: Bailey, Howard W., Stettner, Roger
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/665,738
• Time in Patent Office: 1,581 Days
• Field of Search: 356/5.03, 356/5.04, 356/4.01, 250/332, 250/339.02
• US Class Current: 356/4.01
• 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
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates

Abstract

A three dimensional imaging device is presented which uses single pulse from a pulsed light source for detecting objects enveloped by a light-transmitting medium such as the earth'"'"'s atmosphere or free space. By means of switching off a ramping voltage, individually for each object pixel, the time of arrival of the reflected pulse is recorded. This time is related to the third object dimension. The device consists of the pulsed light source, optics for collecting the reflected light, a sensor for detecting the light, drive and output electronics for timing and signal conditioning of data generated by the sensors and a computer for processing the sensor data and converting it to a three dimensional image. The sensor collects and processes the light data in a unique manner, using a hybrid. The hybrid is actually a two dimensional array of collectors or detectors combined in very close proximity with their own processing electronics. In general, the hybrid is composed of two integrated circuit chips mated together. The two dimensional array defines two dimensions of the image. The processing electronics individually and independently switch off, at high-speed, a time varying voltage when the light pulse, reflected from the object, arrives at the sensor. The final voltages are stored and can be mathematically transformed to the third object dimension. The sensor also records peak light pulse information which can be used to obtain higher resolution in the third dimension.

Claims

1. A device for imaging sections of a three dimensional objects immersed in a light conducting medium comprising:

a pulsed light source;

means for transmitting light from said pulsed light source into said medium;

optics for collecting light from said medium during the time for light to transit from said pulsed light source, reflect from said objects and be collected by said optics;

a sensor means for detecting said collected light, said sensor means comprising

means for converting said collected light into electrical charge,

a hybrid comprising

multiplexing and output circuitry,

a plurality of collection or detection means for collecting or detecting the electrical charge from said conversion means,

a plurality of unit cell processing electronics comprising a plurality of analog memory units, each storing data related to a distinct transit time for a reflected laser pulse from an target pixel, and output amplifier electronics adapted to provide signals to output and multiplexing electronics,

drive electronics for providing voltages and for providing timing for said output amplifier electronics and said output and multiplexing circuitry, and

output electronics for conditioning the signals from said memory units for data processing;

a computer for processing data from said output electronics for real time display.

2. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said unit cell processing electronics, output and multiplexing electronics, and drive and output electronics is adapted to read out said data in real time between pulses from said light source.

3. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said analog memory units are capacitors.

4. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said conversion means is a solid state detector array.

5. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said conversion means is a photocathode.

6. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said conversion means and said hybrid are contained in a vacuum tube.

7. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said conversion means and said hybrid are contained in a vacuum tube with a microchannel plate between them.

8. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 7 wherein said vacuum tube is situated in a magnetic field parallel to the tube axis.

9. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said collection or detection means is an anode.

10. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said collection or detection means is a PIN diode.

11. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said collection or detection means is a PIN diode, a plurality of which are organized into one chip which are electrically and individually connected, by connection means, to the said unit cell processing electronics, a plurality of which are organized into a separate chip.

12. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein said collection or detection means is a anode, a plurality of which are organized into one chip which are electrically and individually connected, by connection means, to the said unit cell processing electronics, a plurality of which are organized into a separate chip.

13. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 11 and 12 wherein said connection means are indium bumps.

14. The three dimensional imaging device of claim 1 wherein said collection or detection means is included in the said unit cell processing electronics.

28. The three dimensional imaging device of claim 1 wherein the said unit cell processing electronics includes transimpedance amplifier means.

29. The three dimensional imaging device of claim 1 wherein the said unit cell processing electronics includes amplifier means.

30. The three dimensional imaging device of claim 1 wherein the said unit cell processing electronics includes filtering means.

31. The three dimensional imaging device of claim 1 wherein the said unit cell processing electronics includes Peak Detector electronics.

32. The three dimensional imaging device of claim 1 wherein the said unit cell processing electronics contains Schmitt Trigger and Memory means.

33. The three dimensional imaging device of claim 28 having an amplifier means wherein the said transimpedance amplifier means and said amplifier means are capacitively coupled to each other.

34. The three dimensional imaging device of claim 28 having an amplifier means wherein the said transimpedance amplifier means and said amplifier means are connected by a high frequency filter.

35. The three dimensional imaging device of claim 32 having an amplifier means wherein the said amplifier means is connected to the said Schmitt Trigger and Memory means by a high frequency filter.

36. The three dimensional imaging device of claim 31 wherein, the said Peak Detector electronics includes capacitors for analog storage of electrical signals related to the peak laser return signals.

37. The three dimensional imaging device of claim 31 wherein the said peak detector electronics includes a timing generator for turning the peak detector on and off.

53. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 4 wherein said solid state detector array amplifies the signal.

55. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein the peak of the light pulse is output as an electrical signal for each of the said collection means.

57. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein each said distinct transit time is obtained by means of disconnection from a ramp voltage.

59. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 55 wherein a peak detector obtains the peak of the light pulse.

61. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 57 wherein a Schmitt Trigger causes the said disconnection form the ramp voltage.

63. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1, wherein said unit cell processing electronics includes amplifiers.

65. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 1 wherein the said unit cell processing electronics includes filters.

67. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 55 wherein the said electrical signal is first stored in an analog memory unit before being output.

69. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 67 wherein the said analog memory unit is a capacitor.

72. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 57 wherein the value of the said ramp voltage at disconnection is stored on an analog memory unit before being output.

74. The device for imaging sections of three dimensional objects immersed in a light conduction medium of claim 72, wherein the said analog memory unit is a capacitor.

15. A sensor for detecting the presence of light, comprising

means for converting said light into electrical charge,

a hybrid comprising

multiplexing and output circuitry,

a plurality of collection or detection means for collecting or detecting the electrical charge from said conversion means,

a plurality of unit cell processing electronics comprising a plurality of analog memory units, each storing data related to a distinct transit time for a reflected laser pulse from an target pixel, and output amplifier electronics adapted to provide signals to output and multiplexing electronics.

16. The sensor for detecting the presence of light of claim 15 wherein said analog memory units are capacitors.

17. The sensor for detecting the presence of light of claim 15 wherein said conversion means is a solid state detector array.

18. The sensor for detecting the presence of light of claim 15 wherein said conversion means is a photocathode.

19. The sensor for detecting the presence of light of claim 15 wherein said conversion means and said hybrid are contained in a vacuum tube.

20. The sensor for detecting the presence of light of claim 15 wherein said conversion means and said hybrid are contained in a vacuum tube with a microchannel plate between them.

21. The sensor for detecting the presence of light of claim 19 wherein said vacuum tube is situated in a magnetic field parallel to the tube axis.

22. The sensor for detecting the presence of light of claim 15 wherein said collection or detection means is an anode.

23. The sensor for detecting the presence of light of claim 15 wherein said collection or detection means is a PIN diode.

24. The sensor for detecting the presence of light of claim 15 wherein said collection or detection means is a PIN diode, a plurality of which are organized into one chip which are electrically and individually connected, by connection means, to the said unit cell processing electronics, a plurality of which are organized into a separate chip.

25. The sensor for detecting the presence of light of claim 15 wherein said collection or detection means is a anode, a plurality of which are organized into one chip which are electrically and individually connected, by connection means, to the said unit cell processing electronics, a plurality of which are organized into a separate chip.

26. The sensor for detecting the presence of light of claim 24 and 25 wherein said connection means are indium bumps.

27. The sensor for detecting the presence of light of claim 15 wherein said collection or detection means is included in the said unit cell processing electronics.

38. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes transimpedance amplifier means.

39. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes amplifier means.

40. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes filtering means.

41. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes Peak Detector electronics.

42. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics contains Schmitt Trigger and Memory means.

43. The sensor for detecting the presence of light of claim 38 having amplifier means wherein the said transimpedance amplifier means and said amplifier means are capacitively coupled to each other.

44. The sensor for detecting the presence of light of claim 38 having amplifier means wherein the said transimpedance amplifier means and said amplifier means are connected by a high frequency filter.

45. The sensor for detecting the presence of light of claim 42 having amplifier means wherein the said amplifier means is connected to the said Schmitt Trigger and Memory means by a high frequency filter.

46. The sensor for detecting the presence of light of claim 41 wherein the said Peak Detector electronics includes capacitors for analog storage of electrical signals related to the peak laser return signals.

47. The sensor for detecting the presence of light of claim 41 wherein the said peak detector electronics includes a timing generator for turning the peak detector on and off.

48. The sensor for detecting the presence of light of claim 15 having amplifier means wherein the said output amplifier means includes column and row selection switching means for each output.

54. The sensor of claim 17 for detecting the presence of light wherein the said solid state detector array amplifies the signal.

56. The sensor for detecting the presence of light of claim 15 wherein the peak of he light pulse is output as an electrical signal for each of the said collection means.

58. The sensor for detecting the presence of light of claim. 15 wherein each said distinct transit time is obtained by means of disconnection from a ramp voltage.

60. The sensor for detecting the presence of light of claim 56 wherein a peak detector obtains the peak of the light pulse.

62. The sensor for detecting the presence of light of claim 58 wherein a Schmitt Trigger causes the said disconnection form the ramp voltage.

64. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes amplifiers.

66. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes amplifiers.

68. The sensor for detecting the presence of light of claim 56 wherein the said electrical signal is first stored in an analog memory unit before being output.

70. The sensor for detecting the presence of light of claim 68 wherein the said analog memory unit is a capacitor.

71. The sensor for detecting the presence of light of claim 58 wherein the value of the said ramp voltage at disconnection is stored on an analog memory unit before being output.

73. The sensor for detecting the presence of light of claim 71 wherein the said analog memory unit is a capacitor.

75. The sensor for detecting the presence of light of claim 15 wherein the said unit cell processing electronics includes a timing generator to prevent contamination of the peak signals from unwanted reflections.

49. A method for imaging sections of three dimensional objects immersed in a light conducting medium comprising the steps of:

generating a series of pulses of light;

transmitting said light into said medium;

collecting light from said medium during the time of transmission and reflection of light from said objects;

detecting said collected light

providing electrical signals from a plurality of positions on the objects with a single light pulse,

storing said electrical signals on a plurality of unit cells corresponding to the said plurality of positions on said objects,

providing signals from said storage means,

converting the signals stored on said storage means to a three-dimensional image of the objects.

50. The method for imaging sections of three dimensional objects immersed in a light conducting medium of method 49 wherein the electrical signals correspond to the transit time of the light to the object positions and back to the transmitter.

51. The method for imaging sections of three dimensional objects immersed in a light conducting medium of method 49 wherein the electrical signals include those corresponding to the peak of the reflected light pulse.

52. The method for imaging sections of three dimensional objects immersed in a light conducting medium of method 50 wherein the electrical signals include those corresponding to the peak of the reflected light pulse.