System and method for remote sensing and/or analyzing spectral properties of targets and/or chemical species for detection and identification thereof

• US 7,315,377 B2
• Filed: 02/10/2004
• Issued: 01/01/2008
• Est. Priority Date: 02/10/2003
• Status: Expired due to Fees

• Current Assignee: University of Virginia Patent Foundation (University of Virginia)
• Original Assignee: University of Virginia Patent Foundation (University of Virginia)
• Inventors: Childers, James M. IV, Holland, Stephen Keith, Krauss, Roland H., Laufer, Gabriel
• Primary Examiner(s): Evans; F. L.
• Application Number:
  US10/544,421
• Publication Number:
  US 20060132780A1
• Time in Patent Office: 1,421 Days
• Field of Search: 356/51, 356/416, 356/418, 356/419, 250/226, 250/338.5, 250/339.01, 250/339.02, 250/339.07
• US Class Current: 356/419
• CPC Class Codes: G01J 2001/4242 Modulated light, e.g. for synchronizing source and detector circuit
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/0235 using means for replacing an element by another, for replacing a filter or a grating
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/32 Investigating bands of a spectrum in sequence by a single detector
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 2021/3137 with selection of wavelengths after the sample
• CPC Class Codes: G01N 2021/317 Special constructive features
• CPC Class Codes: G01N 2021/3531 without instrumental source, i.e. radiometric
• 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 21/3518 Devices using gas filter correlation techniques; Devices using gas pressure modulation techniques

Abstract

A method and a low-cost, robust and simple system for remote sensing and analyzing spectral properties of targets as a means to detect and identify them is introduced. The system can be highly portable but is usable in fixed locations or combination thereof. An aspect of the method and system includes the capability to distribute, modulate, aperture and spectrally analyze radiation emitted or absorbed by a volumetric target chemical species (solid, liquid or gas) or a target surface. Radiation is first collected by a single light gathering device, such as a lens, telescope, or mirror, and then distributed to multiple detectors through spectrally discriminating components and if desired through apertures to achieve this desired detection and identification.

Claims

1. A system for remote sensing and analyzing spectral properties of at least one target and/or chemical species, said system comprising:

a light gathering device that collects and focuses incoming radiation emitted and/or absorbed and/or scattered by the target and/or chemical species to be analyzed;

a folding optical element for directing said collected and focused radiation from said light gathering device to at least one of a plurality of detectors;

at least one spectrally discriminating optical element in front of at least some of said detectors for spectrally resolving said collected radiation;

said detectors, in relative movement with said folding optical element, producing an output signal; and

a driving device to produce said relative movement;

a device or method to monitor phase and frequency of the relative movement; and

a demodulation device, synchronous with said driving device, to demodulate said output signal produced by said detectors.

2. The system of claim 1, wherein said light gathering device comprises a lens.

3. The system of claim 1, wherein said detectors comprise an array.

4. The system of claim 3, wherein said array comprises at least one of a curved array, circular array, ring array, or linear array.

5. The system of claim 3, wherein said array is rotated or oscillated to provide said relative movement.

6. The system of claim 3, wherein said array includes at least one gap, said at least one gap defined as without any active detector and towards which light can be directed when array is not operational.

7. The system of claim 1, wherein said spectrally discriminating optical element comprises at least one of bandpass filters, notch filters, long and short pass filters, diffraction filters or polarizer filters or combination of at least one of a bandpass filter, notch filter, long pass filter, short pass filter or polarizer filter.

8. The system of claim 1, wherein said folding optical element comprises a multifaceted mirror.

9. The system of claim 1, wherein said folding optical element is tilted.

10. The system of claim 9, wherein the tilt is a large reflection angle, wherein large reflection angle provides ability to project the axial ray away from incoming radiation that is focused by the light gathering device.

11. The system of claim 10, wherein said folding optical element is rotated by said driving device to provide said relative movement.

12. The system of claim 10, wherein said plurality of detectors is rotated around folding optical element by said driving device to provide said relative movement.

13. The system of claim 9, wherein the tilt is a small reflection angle, wherein small reflection angle provides ability to project the axial ray toward incoming radiation that is focused by the light gathering device.

14. The system of claim 13, wherein said folding optical element is rotated by said driving device to provide said relative movement.

15. The system of claim 13, wherein said plurality of detectors is rotated by said driving device to provide said relative movement.

16. The system of claim 13, wherein said plurality of detectors is rotated around the line of the axial ray near the focal point by said driving device to provide said relative movement.

17. The system of claim 1, wherein said folding optical element is rotated or oscillated to provide said relative movement.

18. The system of claim 1, wherein said folding optical element comprises a mirror tilted and is located between said plurality of detectors and said light gathering device.

19. The system of claim 1, wherein said folding optical element is angularly oscillated around a pivot relative to said detectors by said driving device to provide said relative movement.

20. The system of claim 19, wherein said folding optical element is tilted.

21. The system of claim 1, wherein said plurality of detectors is linearly oscillated relative to said folding optical element by said driving device to provide said relative movement.

22. The system of claim 21, wherein said folding optical element is tilted.

23. The system of claim 22, wherein said folding optical element is tilted at a large reflection angle.

24. The system of claim 1, wherein said driving device comprises at least one of a digitally or analog controlled motor.

25. The system of claim 1, further comprising an aperture device along the optical path from the target to said detectors to prevent off-axis incoming radiation from impinging on the detectors.

26. The system of claim 25, wherein said aperture device comprises an array of parallel optically transmitting channels or substantially parallel optically transmitting channels in front of said light gathering device.

27. The system of claim 26, wherein said array of parallel or substantially parallel optically transmitting channels is honeycomb structure.

28. The system of claim 25, wherein said aperture device comprises an array of parallel optically transmitting channels or substantially parallel optically transmitting channels behind said light gathering device.

29. The system of claim 28, wherein said array of parallel or substantially parallel optically transparent channels is honeycomb structure.

30. The system of claim 25, wherein said aperture device comprises a mask, whereby said mask allows radiation from said target to pass through to the currently illuminated detector(s) in the cycle sequence, whereby off-axis radiation is blocked or at least substantially blocked from the currently illuminated detector(s) and detector(s) selected to be monitored for generating their reference signal.

31. The system of claim 30, wherein said mask is defined as at least one opaque member with a hole or gap forming an aperture adapted to allow the radiation to pass there through.

32. The system of claim 31, wherein said opaque member is a disk, planar member, or substantially planar member, or member conforming to the general shape of the detector array surface, operating in front of said surface.

33. The system of claim 1, further comprising a processor wherein said processor receives output signals from said detectors and!or demodulation device to separate background effects and noise from output signal to provide a net output that represents the spectral characteristics of the target and use those characteristics to detect andlor identify said targets.

34. The system of claim 33, wherein said detected andlor identified targets are provided for at least one of:

reducing or eliminating danger in public, private or military facilities or spaces or outdoors due to the presence of toxic chemicals, to allow control of chemical or medical manufacturing processes, or to allow control or monitoring of pollution or other processes due to plant or factory emission or other equipment.

35. The system of claim 33, wherein said system is at least partially disposed in a housing defined as hand held device, portable device, fixed location mounted, vehicle mounted, or robotic mounted or personnel mounted.

36. A system for remote sensing and analyzing spectral properties of at least one target and/or chemical species, said system comprising:

a light gathering device that collects, focuses, and directs incoming radiation emitted and/or absorbed and/or scattered by the target and/or chemical species to be analyzed to one of a plurality of detectors;

at least one spectrally discriminating optical element in front of at least some of said detectors for spectrally resolving said collected radiation;

said detectors, in relative movement with said light gathering device, producing an output signal;

a driving device to produce said relative movement between said light gathering device and said detectors;

a device or method to monitor phase and frequency of the relative movement; and

a demodulation device, synchronous with said driving device, to demodulate said output signal produced by said detectors.

37. The system of claim 36, wherein said detectors comprise an array.

38. The system of claim 37, wherein said array comprises at least one of a curved array, circular array, ring array, or linear array.

39. The system of claim 38, wherein said array includes at least one gap, said at least one gap defined as without any active detector and towards which light can be directed when array is not operational.

40. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens with an off-axis focus spinning around its own geometrically central axis, which is aligned with the central axis of said detector array, such that said source radiation focuses on said elements of said detector array, in a sequence.

41. The system of claim 40, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

42. The system of claim 40, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

43. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens spinning around an axis which is off the geometrical center and that coincides with the geometrically central axis of said detector array such that said radiation focuses on said elements of said detector array, in a sequence.

44. The system of claim 43, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

45. The system of claim 43, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

46. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a fixed lens with an off-axis focus and said detector array is rotated around the geometrically central axis of said lens by said driving device such that said radiation focuses on said elements of said detector array, in a sequence.

47. The system of claim 46, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

48. The system of claim 46, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

49. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a fixed lens and said detector array is rotated around an axis offset from but parallel to the geometrically central axis of said lens by said driving device such that said radiation focuses on said elements of said detector array, in a sequence.

50. The system of claim 49, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

51. The system of claim 49, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

52. The system of any one of claims 40, 43, 46, or 49, wherein said array comprises a circular array.

53. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens linearly oscillating relative to said detector array such that said radiation focuses on said elements of said detector array, in a sequence.

54. The system of claim 53, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

55. The system of claim 53, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

56. The system of claim 36, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens and said detector array oscillates linearly relative to the said lens such that said radiation focuses on said elements of said detector array, in a sequence.

57. The system of claim 56, said sequence is defined by the radiation focusing on one of said individual detectors at a time.

58. The system of claim 56, said sequence is defined by the radiation focusing on at least a plurality of said individual detectors one at a time or a plurality at a time.

59. The system of any one of claims 53 or 56, wherein said array comprises a linear array or curved array.

60. The system of claim 36, wherein said driving device comprises at least one of a digital or analog controlled motor.

61. The system of claim 36, further comprising an aperture device along the optical path from the target to said detectors to prevent off-axis incoming radiation from impinging on the detectors.

62. The system of claim 61, wherein said aperture device comprises an array of parallel optically transparent channels or substantially parallel optically transparent channels in front of said light gathering device.

63. The system of claim 62, wherein said array of optically transparent parallel or substantially parallel channels is honeycomb structure.

64. The system of claim 61, wherein said aperture device comprises an array of parallel optically transparent channels or substantially parallel optically transparent channels behind said light gathering device.

65. The system of claim 64, wherein said array of parallel optically transparent channels is honeycomb structure.

66. The system of claim 61, wherein said aperture device comprises a mask, whereby said mask allows radiation from said target to pass there through to currently illuminated detector(s) in the cycle sequence, whereby off-axis radiation is blocked or at least substantially blocked from the currently illuminated detector(s) and detector(s) selected to be monitored for generating their reference signal.

67. The system of claim 66, wherein said mask is defined as at least one opaque member with a hole or gap forming an aperture adapted to allow the radiation to pass there through.

68. The system of claim 67, wherein said opaque member is a disk, planar member, or substantially planar member, or member conforming to the general shape of the detector array surface, operating in front of said surface.

69. The system of claim 36, wherein said spectrally discriminating optical element comprises at least one of bandpass filters, notch filters, long and short pass filters, diffraction filters or polarizer filters or combination of at least one of a bandpass filter, notch filter, long pass filter, short pass filter or polarizer filter.

70. The system of claim 36, further comprising a processor wherein said processor receives output signals from said detectors and/or demodulation device to separate background effects and noise from output signal to provide a net output that represents the spectral characteristics of the target and use those characteristics to detect andlor identify said targets.

71. The system of claim 70, wherein said detected andlor identified targets are provided for at least one of:

reducing or eliminating danger in public, private or military facilities or spaces or outdoors due to the presence of toxic chemicals, to allow control of chemical or medical manufacturing processes, or to allow control or monitoring of pollution or other process due to plant or factory emission or other equipment.

72. The system of claim 70, wherein said system is at least partially disposed in a housing defined as hand held device, portable device, fixed mounted location, vehicle mounted, robotic mounted or personnel mounted.

73. A method for remote sensing and analyzing spectral properties of at least one target and/or chemical species, said method comprising:

collecting and focusing incoming radiation emitted and/or absorbed and/or scattered by the target and/or chemical species to be analyzed, said collecting and focusing being conducted from a gathering location;

directing said focused radiation, said directing being conducted at a directing location;

spectrally analyzing said collected radiation at a spectral analysis location, said spectral analysis produces spectral signature that can be used to identify target;

detecting said directed and spectrally analyzed radiation at a detecting location, wherein said directing location and said detecting location is in relative movement from one another, said detection producing an output signal;

monitoring the phase and frequency of the relative movement; and

demodulating said output signal.

74. The method of claim 73, wherein said collecting and focusing are accomplished using a lens.

75. The method of claim 73, wherein said collected radiation is spectrally analyzed by a plurality of at least one of bandpass filters, notch filters, long and short pass filters, diffraction filters or polarizer filters or combination of at least one of a bandpass filter, notch filter, long pass filter, short pass filter or polarizer filter.

76. The method of claim 73, wherein said detecting is accomplished by a plurality of detectors.

77. The method of claim 76, wherein said detectors comprise an array.

78. The method of claim 77, wherein said array includes at least one gap, said at least one gap defined as without any active detector and towards which light can be directed when array is not operational.

79. The method of claim 73, wherein said directing is accomplished by a folding optical element.

80. The method of claim 79, wherein said folding optical element is tilted.

81. The method of claim 80, wherein the tilt is a large reflection angle, wherein the large reflection angle provides ability to project the axial ray away from the incoming radiation that is focused by the light gathering device.

82. The method of claim 80, wherein the tilt is a small reflection angle, wherein the small reflection angle provides ability to project the axial ray toward the incoming radiation that is focused by the light gathering device.

83. The method of claim 79, wherein said folding optical element comprises a reflecting mirror or multifaceted mirror.

84. The method of claim 79, wherein said folding optical element is rotated or oscillated.

85. The method of claim 79, wherein:

said detecting is accomplished by a plurality of detectors forming an array; and

said detector array is rotated around said tilted folding optical element.

86. The method of claim 79, wherein:

said detecting is accomplished by a plurality of detectors forming an array; and

said detector array is linearly oscillated relative to said tilted folding optical element.

87. The method of claim 73, wherein said relative movement is accomplished by a driving device.

88. The method of claim 87, wherein said driving device comprises at least one of a digitally or analog controlled motor.

89. The method of claim 73, wherein:

said directing is accomplished by a folding optical element; and

said detecting is accomplished by a plurality of detectors.

90. The method of claim 89, further comprising aperturing the incoming radiation to prevent off-axis incoming radiation from impinging on the detectors.

91. A method for remote sensing and analyzing spectral properties of at least one target and/or chemical species, said method comprising:

collecting, focusing, and directing incoming radiation emitted and/or absorbed and/or scatterd by the target and/or chemical species to be analyzed, said collecting, focusing, and directing being conducted from a gathering location;

spectrally analyzing said collected radiation at a spectral analysis location, said spectral analysis produces spectral signature that can be used to identify target;

detecting said directed and spectrally analyzed radiation at a detecting location, wherein said gathering location and said detecting location is in relative movement from one another, said detection producing an output signal;

monitoring the phase and frequency of the relative movement; and

demodulating said output signal.

92. The method of claim 91, wherein said collecting, focusing, and directing are accomplished using a lens.

93. The method of claim 92, wherein said collected radiation is spectrally analyzed by at least one of bandpass filters, notch filters, long and short pass filters, diffraction filters, or polarizer filters or combination of at least one of bandpass filter, notch filter, long pass filter, short pass filter, diffraction filters, or polarizer filter or combination of a bandpass filter, notch filter, long pass filter, short pass filter and polarizer filter.

94. The method of claim 91, wherein said detecting is accomplished by a plurality of detectors.

95. The method of claim 94, wherein said detectors comprise an array.

96. The method of claim 95, wherein said array comprises at least one of a curved array, circular array, ring array, or linear array.

97. The method of claim 95, wherein said array includes at least one gap, said at least one gap defined as without any active detector and towards which light can be directed when array is not operational.

98. The method of claim 91, wherein:

said collecting, focusing, and focusing are accomplished using a lens; and

said detecting is accomplished by a plurality of detectors.

99. The method of claim 98, wherein:

said detectors comprise a detector array; and

said lens with an off-axis focus spinning around its own geometrically central axis, which is aligned with the central axis of said detector array, such that said source radiation focuses on the elements of the detector array, in a sequence.

100. The method of claim 98, wherein:

said detectors comprise a detector array; and

said lens spinning around an axis that is off its geometrical center but that coincides with the geometrically central axis of said detector array such that said radiation focuses on the elements of the detector array, in a sequence.

101. The method of claim 98, wherein:

said detectors comprise an array; and

said lens is fixed with an off-axis focus and said detector array is rotated around the geometrically central axis of said lens by said driving device such that said radiation focuses on the elements of the detector array, in a sequence.

102. The method of claim 98, wherein:

said detectors comprise an array; and

said lens is fixed and said detector array is rotated around an axis offset from but parallel to the geometrically central axis of said lens by said driving device such that said radiation focuses on the elements of the detector array, in a sequence.

103. The method of claim 98, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens linearly oscillating relative to said detector array such that said radiation focuses on the elements of the detector array, in a sequence.

104. The method of claim 98, wherein:

said detectors comprise an array; and

said light gathering device comprises a lens and said detector array oscillates linearly relative to the said lens such that said radiation focuses on the elements of the detector array, in a sequence.

105. The method of claim 98, wherein said relative movement is accomplished by a driving device.

106. The method of claim 98, further comprising aperturing the incoming radiation to prevent off-axis incoming radiation from impinging on the detectors.