Very fast time resolved imaging in multiparameter measurement space

• US 20040031906A1
• Filed: 06/10/2003
• Published: 02/19/2004
• Est. Priority Date: 04/26/2000
• Status: Active Grant

• Current Assignee: Anthony D. Glecker
• Original Assignee: Anthony D. Glecker
• Inventors: Glecker, Anthony D
• Granted Patent: US 7,227,116 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: G01J 11/00 Measuring the characteristics of individual optical pulses or of optical pulse trains
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/0294 Multi-channel spectroscopy
• CPC Class Codes: G01J 3/04 Slit arrangements slit adjustment
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/2889 Rapid scan spectrometers; Time resolved spectrometry
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 3/447 Polarisation spectrometry
• CPC Class Codes: G01J 4/00 Measuring polarisation of light
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 2021/6417 Spectrofluorimetric devices
• CPC Class Codes: G01N 2021/6423 Spectral mapping, video display
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/6408 with measurement of decay time, time resolved fluorescence
• CPC Class Codes: G01N 21/6456 : Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01S 17/89 : for mapping or imaging
• CPC Class Codes: G01S 7/481 : Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4817 : relating to scanning
• CPC Class Codes: G04F 13/02 : using optical means
• CPC Class Codes: G04F 13/026 : Measuring duration of ultra-short light pulses, e.g. in the pico-second range; particular detecting devices therefor photometry, radiation pyrometry G01J1/00, G01J5/00; non-linear optics G02F1/35
• CPC Class Codes: H01J 43/00 : Secondary-emission tubes; Electron-multiplier tubes dynamic electron-multiplier tubes H01J25/76

Abstract

Plural electronic or optical images are provided in a streak optical system, as for instance by use of plural slits instead of the conventional single slit, to obtain a third, fourth, etc. dimension—rather than only the conventional two, namely range or time and azimuth. Such additional dimension or dimensions are thereby incorporated into the optical information that is to be streaked and thereby time resolved. The added dimensions may take any of an extremely broad range of forms, including wave-length, polarization state, or one or more spatial dimensions—or indeed virtually any optical parameter that can be impressed upon a probe beam. Resulting capabilities remarkably include several new forms of lidar spectroscopy, fluorescence analysis, polarimetry, spectropolarimetry, and combinations of these, as well as a gigahertz wavefront sensor.

Claims

1. A streak lidar imaging system for measurements of a medium with any objects therein;

said system comprising;

a light source for emitting at least one beam into such medium;

an imaging device for receiving light reflected from such medium and forming plural images, arrayed along a streak direction, of the reflected light;

wherein the imaging device comprises plural slits for selecting particular bands of the plural images respectively; and

a device for displacing all the plural images along the streak direction.

2. The system of claim 1, wherein:

the imaging device comprises an optical device;

the plural images are optical images; and

the displacing device comprises a module for displacing the plural optical images.

3. The system of claim 2, wherein:

the displacing device comprises an electromechanical device.

4. The system of claim 3, wherein:

the electromechanical device comprises at least one scanning microelectromechanical mirror.

5. The system of claim 3, wherein:

the electromechanical device comprises an array of scanning microelectromechanical mirrors.

6. The system of claim 2, wherein:

the displacing device comprises an electrooptical device.

7. The system of claim 1, wherein:

the imaging device comprises an electronic device;

the plural images are electronic images; and

the displacing device comprises a module for displacing the plural electronic images.

8. The system of claim 7, wherein:

the displacing device comprises electronic deflection plates.

9. The system of claim 7, wherein the imaging device comprises:

an optical front end that forms a single optical image of the reflected light; and

an electronic stage receiving the single optical image and forming therefrom the plural electronic images.

10. The system of claim 7, wherein the imaging device comprises:

an optical front end that forms plural optical images of the reflected light; and

an electronic stage receiving the plural optical images and forming therefrom the plural electronic images.

11. The system of claim 1:

wherein the displacing device forms from each of the plural images a respective streak image;

whereby the displacing device forms, from the plural images considered in the aggregate, a corresponding array of plural streak images; and

further comprising a device for receiving the array of plural streak images and in response forming a corresponding composite signal.

12. The system of claim 1, wherein:

the plural slits operate on the images in optical form.

13. The system of claim 1, wherein:

the plural slits operate on the images in electronic form.

14. The system of claim 1, wherein:

the imaging device comprises a module for forming substantially a continuum of images of the reflected beam; and

each of the plural slits selects a particular image band from the continuum.

15. The system of claim 1, wherein:

the light source comprises an optical module for emitting at least one thin, fan-shaped beam into such medium;

the imaging device comprises an optical module for receiving at least one thin, fan-shaped beam reflected from such medium; and

at least one of the optical modules comprises an optical unit for orienting a thin dimension of the reflected beam along the streak direction.

16. The system of claim 1, wherein:

the imaging device comprises an optical module for forming the plural images as images of the at least one reflected beam at discrete optical wavelengths, respectively.

17. The system of claim 1, wherein:

the imaging device comprises an optical module for forming the plural images as images of the at least one reflected beam in different polarization states, respectively.

18. The system of claim 1, wherein:

the imaging device comprises an optical device for forming the plural images from different angular sectors, respectively, of the at least one reflected beam.

19. The system of claim 18, wherein:

the imaging device further comprises an optical device for rearranging image elements in each angular sector to form a single line image for that sector.

20. The system of claim 19, wherein:

the optical device comprises remapping optics.

21. The system of claim 20, wherein:

the remapping optics comprise a fiber-optic or laminar-optic module.

22. The system of claim 20, wherein:

the remapping optics comprise a lenslet array.

23. The system of claim 1, wherein:

the light source comprises means for emitting plural beams into such medium; and

the imaging device comprises;

means for receiving plural beams of the reflected light from such medium, and

an optical device for forming the plural images from, respectively, the plural reflected beams.

24. The system of claim 1, wherein:

the light source comprises an emitter for emitting light in a wavelength region at or near 1½

microns.

25. The system of claim 24, wherein:

the imaging device comprises an upconverter for generating light at or near the visible wavelength region in response to the light at or near 1½

microns.

26. The system of claim 25, wherein:

the upconverter comprises ETIR material.

27. The system of claim 1, wherein:

the light source comprises means for emitting the at least one beam into such medium that is selected from the group consisting of;

a generally clear fluid above a generally hard surface;

a turbid medium, including but not limited to ocean water, wastewater, fog, clouds, smoke or other particulate suspensions;

a diffuse medium, including but not limited to foliage at least partially obscuring a landscape.

28. A lidar imaging system for optical measurements of a medium with any objects therein;

said system comprising;

a light source for emitting at least one light pulse into such medium; and

means for receiving the at least one light pulse reflected from such medium and for forming from each reflected pulse a set of plural substantially simultaneous output images, each image representing reflected energy in two dimensions.

29. The system of claim 28:

wherein the light source comprises means for emitting a series of light pulses into such medium, each of the pulses in the series generating a corresponding such image set;

whereby the receiving means generate a sequence of plural corresponding image sets; and

further comprising means for storing the sequence of corresponding image sets.

30. The system of claim 28, wherein:

the receiving means comprise means for allocating image elements, in each image of the set, as among (1) azimuth, (2) range or time, and (3) an extrinsic measurement dimension.

31. The system of claim 30, wherein:

the extrinsic measurement dimension is wavelength.

32. The system of claim 30, wherein:

the extrinsic measurement dimension is polarization state.

33. The system of claim 30, wherein:

the extrinsic measurement dimension is a spatial selection.

34. The system of claim 28, wherein:

the receiving means comprise means for causing the images in the set to be substantially contiguous.

35. The system of claim 28, wherein:

the receiving means comprise means for receiving the reflected light pulse as a beam with a cross-section that has an aspect ratio on the order of 1;

1.

36. The system of claim 35, wherein:

the light source comprises means for emitting the at least one light pulse as a beam with a cross-section that has an aspect ratio on the order of 1;

1.

37. The system of claim 28, wherein:

the receiving means comprise means for forming the images in such a way that the two dimensions are range/time and output-image azimuth, for a particular extrinsic dimension that corresponds to each output image respectively.

38. The system of claim 28, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a generally clear fluid above a generally hard surface.

39. The system of claim 28, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a turbid medium, including but not limited to ocean water, wastewater, fog, clouds, smoke or other particulate suspensions.

40. The system of claim 28, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a diffuse medium, including but not limited to foliage at least partially obscuring a landscape.

41. An optical system comprising:

a first lenslet array for performing a first optical trans-formation on an optical beam; and

a second lenslet array, in series with the first array, for receiving a transformed beam from the first array and performing a second optical transformation on the transformed beam.

42. The system of claim 41, wherein:

one of the arrays comprises image-plane defining lenslets to define image elements of the beam; and

the other array comprises deflecting lenslets to selectively deflect beam elements to reconfigure an image transmitted in the beam.

43. The system of claim 42, wherein:

the one of the arrays that defines the image elements is the first array.

44. The system of claim 42, further comprising:

means defining an image carried by the beam; and

wherein the first array is positioned substantially at a focal plane of the image.

45. The system of claim 44, wherein the image-defining means comprise:

a lidar source emitting an excitation beam to a region of interest; and

collection optics receiving a reflection of the excitation beam from the region and focusing the reflection at the focal plane.

46. The system of claim 45:

wherein the two transformations, considered together, comprise selectively imaging particular components of the beam onto plural slits following the second array; and

further comprising means for streaking images from both slits for reimaging at a detector.

47. The system of claim 44, wherein:

the first array also relays the image from the focal plane to the second array.

48. The system of claim 47, wherein:

the second array is substantially in a plane, said plane being disposed substantially at the relayed image.

49. The system of claim 41, wherein:

the two transformations, considered together, comprise selectively imaging particular components of the beam onto plural slits following the second array.

50. A streak lidar imaging system for making measurements of a medium with any objects therein;

said system comprising;

a light source for emitting into such medium a beam in a substantially eye-safe wavelength range;

an imaging device for receiving light reflected from such medium and forming an image of the reflected light;

an upconverter for generating light at or near the visible wavelength region in response to the reflected light in a substantially eye-safe wavelength range; and

a device for displacing the image along a streak direction.

51. The system of claim 50, wherein:

the upconverter is positioned in the system after the displacing device.

52. The system of claim 50, wherein:

the upconverter comprises ETIR material.

53. The system of claim 50, wherein:

the displacing device is positioned in the system after the upconverter.

54. The system of claim 50, wherein:

the light source emits said beam in a wavelength range at substantially 1½

microns.

55. A streak lidar imaging system comprising:

a light source for emitting a beam;

an imaging device for receiving light originating from the source and for forming an image of the received light;

at least one microelectromechanical mirror for displacing the image along a streak direction; and

an image-responsive element for receiving and responding to the displaced image.

56. The system of claim 55, wherein:

the at least one mirror comprises an array of multiple microelectromechanical mirrors.

57. The system of claim 55, for use with an optical medium and wherein:

the light source comprises means for emitting the beam into such medium; and

the imaging device comprises means for receiving light reflected from such medium and forming an image of the reflected light.

58. The system of claim 55, wherein:

the light source comprises a resonant device; and

the imaging device comprises means for causing imperfections in resonance of the resonant device to modulate the image.

59. The system of claim 58, particularly for use with a resonant device that comprises a laser;

and wherein;

the imaging device comprises means for causing imperfections in optical wavefronts from the laser to modulate the image.

60. The system of claim 59, wherein:

the causing means comprise means for deflecting elements of said beam in response to local imperfections in said coherence.

61. The system of claim 60, wherein:

the deflecting means comprise at least one lenslet array.

62. A spatial mapping system for mapping a region;

said system comprising;

a light source for emitting at least one thin, fan-shaped beam from a moving emission location toward such region, a thin dimension of the beam being oriented generally parallel to a direction of motion of the emission location;

an imaging device for receiving light reflected from such region and forming an image of the reflected light;

means for separating the reflected light to form plural reflected beam images representing different aspects of such region, respectively; and

an image-responsive element for receiving and responding to the plural beam images.

63. The system of claim 62, wherein:

the separating means comprise means for discriminating between spatially different aspects of such region.

64. The system of claim 62, wherein:

the separating means comprise means for discriminating between aspects of such region that are carried in portions of the beam received at different angles.

65. The system of claim 64, wherein:

the discriminating means comprise means for forming discrete plural reflected beam images from portions of the beam received at different angular ranges, respectively.

66. The system of claim 62, wherein:

the separating means comprise means for discriminating between aspects of such region that are carried in different polarization states of the beam.

67. The system of claim 62, wherein:

the separating means comprise means for discriminating between aspects of such region that are carried in different spectral components of the beam.

68. The system of claim 62, wherein:

the separating means comprise means for discriminating between combinations of two or more different aspects of such region that are carried in different characteristics of the beam, at least one of which characteristics is selected from among;

spatially different aspects of the beam,

different polarization states of the beam, and

different spectral components of the beam.

69. The system of claim 68, wherein:

at least two of said characteristics are selected from said spatial, polarization and spectral characteristics.

70. The system of claim 62, wherein the emission location is selected from the group consisting of:

a spacecraft;

an aircraft;

another type of vehicle; and

another type of moving platform.

71. The system of claim 62, wherein:

the emission location is a fixed light source cooperating with a scanning system to provide a moving image of the light source.

72. The system of claim 62, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a generally clear fluid above a generally hard surface.

73. The system of claim 62, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a turbid medium, including but not limited to ocean water, wastewater, fog, clouds, smoke or other particulate suspensions.

74. The system of claim 62, wherein:

the light source comprises means for emitting the at least one beam into such medium that is a diffuse medium, including but not limited to foliage at least partially obscuring a landscape.

75. A spatial mapping system for mapping a region;

said system comprising;

a light source for emitting a beam whose cross-section has an aspect ratio on the order of 1;

1, from a moving emission location toward such region;

an imaging device for receiving light reflected from such region and forming an image of the reflected light;

means for separating the reflected light to form plural reflected beam images representing different aspects of such region, respectively; and

an image-responsive element for receiving and responding to the plural beam images.

76. The system of claim 75, wherein:

the imaging device comprises means for receiving the reflected light from such region as a reflected-beam whose cross-section has an aspect ratio on the order of 1;

1.

77. A spectrometric analytical system for analyzing a medium with any objects therein;

said system comprising;

a light source for emitting substantially at least one pencil beam toward such medium;

an imaging device for receiving light reflected from such medium and forming an image of the reflected light;

means for separating the reflected light along one dimension to form plural reflected beam images arrayed along said dimension and representing different aspects of the medium, respectively;

optical-dispersing means for forming a spectrum from at least one of the plural images, by dispersion of the at least one image along a dimension generally orthogonal to the said dimension; and

an image-responsive element for receiving and responding to the plural beam images.

78. The system of claim 77, wherein:

the dispersing means comprise means for forming a spectrum from each of the plural images, respectively.

79. The system of claim 77, wherein:

the separating means comprise means for separating the reflected light to form plural images representing spatially different aspects of the beam, respectively.

80. The system of claim 77, wherein:

the separating means comprise means for separating the reflected light to form plural images representing different polarization states of the beam, respectively.

81. The system of claim 77, wherein:

the separating means comprise means for separating the reflected light to form plural images representing different spectral constituents of the beam, respectively.

82. The system of claim 77, wherein:

the separating means comprise means for separating the reflected light to form plural images representing combinations of two or more different aspects of such medium that are carried in different characteristics of the beam, at least one of which characteristics is selected from among;

spatially different aspects of the beam,

different polarization states of the beam, and

different spectral components of the beam.

83. A wavefront sensor, for evaluating a light beam from an optical source;

said sensor comprising;

optical components for receiving such beam from such source;

optical components for subdividing small portions of such beam to form indicator subbeams that reveal a direction of substantially each of said small portions; and

optical components for steering the indicator subbeams to fall along at least one slit;

means for streaking light that passes through the at least one slit; and

means for capturing the streaked light during a streaking duration.

85. The system of claim 83, particularly for use with a resonant optical source;

and wherein;

the receiving and subdividing components comprise means for causing imperfections in optical wavefronts from the resonant source to modify the light that passes through the at least one slit.

86. The system of claim 85, wherein:

the receiving, subdividing and steering components comprise at least one lenslet array.

87. The system of claim 86, wherein:

the receiving, subdividing and steering components comprise at least two lenslet arrays in optical series.

88. The system of claim 87, wherein the lenslet arrays comprise:

one array that defines image elements at or near a focal plane of such beam; and

another array that receives the image elements relayed from the first array, and that steers light from the image elements to the at least one slit.

89. The system of claim 86, wherein:

the receiving, subdividing and steering components comprise at least one lenslet array in optical series with at least one fiber-optic remapping device.

84. The system of claim 84, wherein:

the at least one slit comprises plural slits.

90. A spectrometric analytical system for analyzing a medium with any objects therein;

said system comprising;

a light source for emitting substantially at least one beam toward such medium;

an imaging device for receiving light reflected from such medium and forming plural images of the reflected light;

optical or electronic means for streaking the plural images;

an image-responsive element for receiving and responding to the plural beam images; and

a computer for extracting fluorescence-lifetime information from a signal produced by the image-responsive element.

91. The system of claim 90, wherein the at least one beam comprises:

at least one pencil beam.

92. The system of claim 90, wherein the imaging device comprises:

a hyperspectral optical system.

93. The system of claim 92, wherein the imaging device further comprises:

a plural-wavelength optical system wherein each of plural wavelength bands is arrayed along a length dimension of a respective slit-shaped image.