Micromechanical and related lidar apparatus and method, and fast light-routing components

• US 20060132752A1
• Filed: 12/16/2004
• Published: 06/22/2006
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: Arete Associates
• Original Assignee: David M. Kane
• Inventors: Kane, David M.
• Granted Patent: US 7,440,084 B2
• Time in Patent Office: Days
• US Class Current: 356/5.20
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3538 based on displacement or deformation of a liquid controlling the intensity of light by displacement or deformation of a fluid in general G02B26/004; fluid-filled lens of variable focal length G02B3/14
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3588 of the processed beams, i.e. controlling during switching of orientation, alignment, or beam propagation properties such as intensity, size or shape
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52

Abstract

Several systems and a method are taught for rapid modulation of a light beam in lidar and other imaging. Most of these involve micromechanical and other very small control components. One such unit is a light-switching fabric, based on displacement of liquid in a tube that crosses a junction of two optical waveguides. In some forms, the fabric is preferably flexible to enable folding or coiling to form a two-dimensional face that interacts with optical-fiber ends an opposed fiber bundle. The rapid operation of the switch fabric enables it to be used as a beam-splitter, separating incoming and return beams; and also to form pulses from supplied CW light. Other control components include micromechanical mirrors (e. g. MEMS mirrors) operated in arrays or singly, liquid-crystal devices, and other controlled-birefringence cells. Some of these devices are placed within an optical system for directional light-beam steering.

Claims

1. A system for use with one or more features to be detected and ranged;

said system comprising;

a source for generating a lidar beam;

at least one transceiver for directing the generated beam to, and collecting light reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

a polarizing beam splitter for passing light from the source to the transceiver, losing no more than a few percent of such light passing therethrough, and from the transceiver to the detector.

2. The system of claim 1, wherein:

in passing light bidirectionally to and from a particular point of such one or more features, the splitter passes light through substantially a single corresponding common point of a corresponding transceiver.

3. The system of claim 1, wherein:

in passing light bidirectionally to and from a particular point of such one or more features, the splitter passes light through substantially a single corresponding common point of the splitter.

4. The system of claim 1, wherein:

the splitter is a fractionally-transmitting optical element.

53. The system of claim 1, further comprising:

a controller for controlling the source and synchronizing the detector with the source.

54. The system of claim 53, wherein:

the controller also comprises means for interpreting the time-resolved light to detect and range such one or more features.

55. The system of claim 54, further comprising:

means controlled by the interpreted light for imaging, avoiding, meeting, or otherwise navigating relative to such one or more features.

56. The system of claim 55, wherein the controlled means comprise a vehicle having:

at least partly automatic navigation;

or

an advisory system for a human operator.

57. The system of claim 1, wherein:

the lidar-beam source comprises means for producing the beam in a form selected from;

light pulses; and

modulated continuous-wave light.

5. A system for use with one or more features to be detected and ranged;

said system comprising;

a source for generating a lidar beam;

at least one transceiver for directing the generated beam to, and collecting light reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

a beam splitter for passing light from the source to the transceiver, and from the transceiver to the detector;

wherein the splitter is actively switched to route the generated beam from the source and reflected beam to the detector.

85. The system of claim 5, further comprising:

a controller for controlling the source and synchronizing the detector with the source.

6. A system for use with one or more features to be detected and ranged;

said system comprising;

a lidar-beam source;

at least one transceiver for directing the beam to, and collecting light reflected from, such one or more features; and

a lidar detector for time-resolving the reflected beam;

wherein in passing light bidirectionally to and from a particular point of such one or more features, the transceiver passes light through substantially a single corresponding common point of the transceiver.

7. The system of claim 6, wherein:

the lidar detector comprises means for time-resolving the reflected beam by distributing successive signals along a nontemporal domain.

8. The system of claim 7, wherein:

the nontemporal domain comprises a streak-tube screen.

9. The system of claim 6, wherein:

the transceiver comprises a fiber-optic element and free-space imaging optics; and

the imaging optics establish conjugate points of such one or more features for substantially each fiber of the fiber-optic element.

86. The system of claim 6, further comprising:

a controller for controlling the source and synchronizing the detector with the source.

10. A system for use with one or more features to be detected and ranged;

said system comprising;

a lidar light-beam source;

at least one transceiver for directing a lidar beam from the source to, and collecting the beam reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

means for steering successive time segments of the beam to and from particular points, selectively, of such one or more features;

said means being chosen from the group consisting of;

at least one micromechanical mirror;

at least one optical-switching fabric;

at least one liquid-crystal display;

at least one device having signal-controlled birefringence; and

at least one other type of device employing non-linear optical material.

11. The system of claim 10, wherein:

the at least one transceiver comprises plural transceivers; and

the steering means comprise means for successively selecting different ones of the transceivers.

12. The system of claim 10, wherein:

the steering means comprise means for successively selecting different particular points addressed through a transceiver.

87. The system of claim 10, further comprising:

a controller for controlling the source and synchronizing the detector with the source.

13. A system for use with features to be detected and ranged;

said system comprising;

a lidar light-beam source;

plural transceivers each for directing a lidar beam from the source to, and collecting light reflected from, a particular one or more of such features respectively;

a lidar detector for time-resolving the reflected beam; and

means for steering successive time segments of the beam to and from particular ones, selectively, of the plural transceivers respectively.

14. The system of claim 13, wherein:

the steering means comprise means for successively selecting different particular points addressed through a transceiver.

88. The system of claim 13, further comprising:

a controller for controlling the source and synchronizing the detector with the source.

15. A system for use with one or more features to be detected and ranged;

said system comprising;

a lidar light-beam source;

at least one transceiver for directing a lidar beam from the source to, and collecting the beam reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

one or more micromechanical devices for routing the beam.

16. The system of claim 15, wherein:

the devices comprise an array of multiple micromechanical devices.

17. The system of claim 16, wherein:

the devices comprise a fabric made up of an array of multiple micromechanical switches.

18. The system of claim 17:

wherein the switches are regularly arrayed according to a coordinate system; and

further comprising a processor having means for controlling the switches in common, in groupings by dimensions of the coordinate system.

19. The system of claim 18, wherein:

the coordinate system is substantially rectangular; and

the groupings of switches are substantially by row and column of the array.

20. The system of claim 18, wherein:

the coordinate system is substantially closest-packing; and

the groupings of switches are substantially by linear sequence within the array.

21. The system of claim 18, wherein:

the coordinate system is substantially polar or spiral; and

the groupings of switches are substantially by polar coordinates or spiral raster within the array.

22. The system of claim 16:

wherein the array comprises multiple mirrors; and

further comprising a processor having means for controlling mechanical manipulation of the mirrors.

23. The system of claim 22, wherein:

the mirrors are regularly arrayed according to a coordinate system; and

the processor comprises means for controlling the mirrors in common, in groupings by dimensions of the coordinate system.

24. The system of claim 23, wherein:

the coordinate system is substantially rectangular; and

the groupings of mirrors are substantially by row and column of the array.

25. The system of claim 24, wherein:

the processor comprises means for controlling the mirrors to provide a ripple-propagating row or column corresponding to features of the at least one transceiver.

26. The system of claim 23, wherein:

the coordinate system is substantially closest-packing; and

the groupings of mirrors are substantially by linear sequence within the array.

27. The system of claim 23, wherein:

the coordinate system is substantially polar or spiral; and

the groupings of mirrors are substantially by polar coordinates or spiral raster within the array.

28. The system of claim 15, wherein:

the one or more mechanical devices comprise at least one mirror successively angled to select particular linear groups of features of the at least one transceiver.

29. The system of claim 28, wherein:

the at least one mirror is successively angled about an axis defined along substantially a single direction.

30. The system of claim 15, wherein:

the one or more mechanical devices comprise at least one mirror successively angled to select individual pixels or pixel groups of the at least one transceiver.

31. The system of claim 30, wherein:

the at least one mirror is successively angled about plural axes defined along corresponding plural directions.

32. A system for use with one or more features to be detected and ranged;

said system comprising;

a lidar light-beam source;

at least one transceiver for directing a lidar beam from the source to, and collecting the beam reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

one or more liquid-crystal devices for routing the beam.

33. The system of claim 32:

wherein the liquid-crystal devices comprise an array of multiple liquid-crystal devices regularly arranged according to a coordinate system; and

further comprising a processor having means for controlling the liquid-crystal devices in common, in groupings by dimensions of the coordinate system.

34. The system of claim 33, wherein:

the coordinate system is substantially rectangular; and

the groupings of liquid-crystal devices are substantially by row and column of the array.

35. The system of claim 33, wherein:

the coordinate system is substantially closest-packing; and

the groupings of liquid-crystal devices are substantially by linear sequence within the array.

36. The system of claim 33, wherein:

the coordinate system is substantially polar or spiral; and

the groupings of liquid-crystal devices are substantially by polar coordinates or spiral raster within the array.

37. A system for use with one or more features to be detected and ranged;

said system comprising;

a lidar light-beam source;

at least one transceiver for directing a lidar beam from the source to, and collecting the beam reflected from, such one or more features;

a lidar detector for time-resolving the reflected beam; and

one or more controlled-birefringence or other nonlinear-optics devices for routing the beam.

38. The system of claim 37:

wherein the one or more devices are controllable to provide variable optical deflection; and

further comprising a processor for operating the devices at three or more control levels, to enable corresponding multiple deflection levels for each device.

39. The system of claim 37:

wherein the devices comprise an array of multiple controlled-birefringence or other nonlinear-optics devices, regularly arranged according to a coordinate system; and

further comprising a processor for controlling the controlled-birefringence or other nonlinear-optics devices in groupings by dimensions of the coordinate system.

40. The system of claim 39, wherein:

the coordinate system is substantially rectangular; and

the groupings of devices are substantially by row and column of the array.

41. The system of claim 39, wherein:

the coordinate system is substantially closest-packing; and

the groupings of devices are substantially by linear sequence within the array.

42. A system for use with one or more features;

said system comprising;

a source for generating a light beam;

a fabric made up of micromechanical light switches for routing the light beam to such features selectively.

43. The system of claim 42:

further comprising at least one transmitter for directing the beam to such one or more features; and

wherein the fabric directs light to particular portions of the transmitter.

44. The system of claim 43, further comprising:

a processor for controlling the switches.

45. The system of claim 43, wherein:

the fabric is arranged in three dimensions to provide groups of the switches aligned with the particular portions of the transmitter.

46. The system of claim 43, wherein:

the transmitter presents an at-least-two-dimensional array of optical conductors corresponding with the switch groups.

47. The system of claim 43, wherein:

the fabric is folded to provide plural planes of the switches.

48. The system of claim 43, wherein:

the fabric is coiled to provide plural layers of the switches.

49. The system of claim 43, wherein:

the transmitter comprises a transceiver for directing the beam to and from such one or more features, to collect reflected portions of the beam; and

the fabric directs light to and from said particular portions of the transmitter.

50. The system of claim 49:

further comprising a detector receiving the reflected beam from the transmitter and fabric; and

wherein the fabric directs light from the source and to the detector, respectively.

51. The system of claim 42, wherein:

the source is embedded within the fabric.

52. The system of claim 51, further comprising:

a detector also embedded within the fabric.

58. A system for use with input or output devices, or both, and with at least one light beam;

said system comprising;

a fabric made up of micromechanical light switches for routing such light beam selectively; and

the fabric being arrangeable in three dimensions to provide groups of the switches aligned with particular such input or output devices, or both.

59. The system of claim 58, wherein:

the fabric is arranged in three dimensions to align with particular such input or output devices, or both.

60. The system of claim 59, in combination with the input or output devices, or both, and wherein:

the input or output devices, or both, present an at-least-two-dimensional array of optical conductors corresponding with the switch groups.

61. The system of claim 60, wherein:

the groups of switches direct light to and from particular portions of the array.

62. The system of claim 58, wherein:

the fabric is foldable to provide plural planes of the switches.

63. The system of claim 62, wherein:

the fabric is folded to provide plural planes of the switches.

64. The system of claim 58, wherein:

the fabric is coilable to provide plural layers of the switches.

65. The system of claim 64, wherein:

the fabric is coiled to provide plural layers of the switches.

66. A system for use with light that is reflected, by a reflecting entity, from a source to a destination;

said system comprising;

a bidirectional beam splitter made up of micromechanical light switches for routing such light beam selectively;

the switches being switchable rapidly enough to establish at least two distinct routes comprising;

a route from such source to such reflecting entity, at a first time; and

a route from such reflecting entity to such destination, at a second time;

wherein the switches are switchable rapidly enough to change routing between the first route and the second during a time interval between passage of such light from such source to such reflecting entity and return of the same reflected light from such reflecting entity.

67. The system of claim 66, for use with such light that is a pulse beam or a modulated continuous-wave beam;

and wherein;

the pulse or a modulation signature, respectively, is of duration on the order of milliseconds, or longer.

68. The system of claim 66, for use with such light that is a pulse beam or a modulated continuous-wave beam;

and wherein;

the pulse or a modulation signature, respectively, is of duration on the order of microseconds to hundreds of microseconds.

69. The system of claim 66, for use with such light that is a pulse beam or a modulated continuous-wave beam;

and wherein;

the pulse or a modulation signature, respectively, is of duration on the order of nanoseconds to hundreds of nanoseconds.

70. The system of claim 66, for use with such light that is a pulse beam or a modulated continuous-wave beam;

and wherein;

the pulse or a modulation signature, respectively, is of duration on the order of picoseconds, or less, to hundreds of picoseconds.

71. The system of claim 66, wherein:

the beam splitter has substantially no reflecting surface that loses more than a few percent of such light passing along at least the first route therethrough.

72. An optical system for use with one or more features to be characterized by light reflected therefrom;

said system comprising;

a source for generating a light beam;

a detector receiving the reflected beam;

plural means for directing the beam from the source to such one or more features and collecting the reflected beam from such one or more features;

each one of said plural directing means comprising a macroscopic optical component, for addressing multiple rays at multiple distinctly different points of each one of said features; and

a directional scanner for selectively pointing the directing means, said scanner being disposed;

preceding an exit pupil, for light passing from the directing means to such one or more features;

or

following an reentry pupil, for light from passing from such one or more features to the directing means;

or

both preceding an exit pupil and following an entry pupil.

73. The system of claim 72, wherein:

the macroscopic optical element comprises a multiple-optical-fiber light pipe, or a lens or prism or grating.

74. The system of claim 72, wherein:

the system is a lidar system; and

the source generates a pulse beam or a modulated continuous-wave beam.

75. The system of claim 72, wherein:

the directing means comprise at least one micromechanical device.

76. The system of claim 75, wherein:

the at least one micromechanical device comprises a steerable mirror.

77. The system of claim 75, wherein:

the at least one device comprises a steerable array of mirrors.

78. The system of claim 75, wherein:

the device comprises an array of optical switches.

79. The system of claim 75, wherein:

the device comprises a three-dimensionally arranged array of optical switches.

80. The system of claim 72, wherein:

the directing means comprise at least one liquid-crystal device.

81. The system of claim 72, wherein:

the directing means comprise at least one controlled-birefringence device or other nonlinear-optics device.

82. A method for concurrently producing light pulses and distributing the pulses to features, for use in detecting and ranging the features;

said method utilizing a light source, at least one light detector, and an array of micromechanical optical switches, and comprising the steps of;

operating the source to form a generally continuous light beam;

during the operating step, passing the generally continuous light beam into the array of switches;

during the passing step, setting the switches to direct the generally continuous beam toward a first one of the features;

then resetting the switches to;

interrupt directing of the generally continuous beam toward the first one of the features, whereby the setting and resetting steps cooperate to form a pulse of light directed toward the first one of the features, and

concurrently route the pulse of light reflected from the first one of the features to the at least one detector;

also concurrently with the resetting step, time-resolving the reflected light to detect and range the first one of the features; and

then iterating the setting, resetting and time-resolving steps, but with respect to second and subsequent ones of the features, to successively detect and range the second and subsequent ones.

83. The method of step 82, wherein:

the resetting step interrupts said directing step by instead directing the generally continuous beam toward the next one of the features in turn, substantially immediately with substantially negligible intervening interval; and

the detection and ranging of the second and some subsequent features proceeds while directing of pulses with respect to later features is ongoing.

84. The method of step 83, said method utilizing multiple light detectors;

and wherein;

the iterating step routes subsequent reflected pulses of light to respective different ones of the multiple detectors.