System and Method for Combined Raman, SWIR and LIBS Detection

• US 20110080577A1
• Filed: 10/06/2010
• Published: 04/07/2011
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Gardner, Charles W. JR., Nelson, Matthew, Treado, Patrick
• Granted Patent: US 8,582,089 B2
• Time in Patent Office: Days
• US Class Current: 356/73
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0221 the fibers defining an entry slit
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/1738 Optionally different kinds of measurements; Method being valid for different kinds of measurement
• CPC Class Codes: G01N 2021/174 either absorption-reflection or emission-fluorescence
• CPC Class Codes: G01N 2021/1744 either absorption or scatter
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma
• CPC Class Codes: G01N 33/227 Explosives, e.g. combustive properties thereof detecting explosives in air G01N33/0057

Abstract

A system and method for the detection and identification of explosives and explosive residues using a combination of SWIR, Raman, and LIBS spectroscopy techniques, including imaging. A region of interest may be surveyed to identify a target area, wherein the target area comprises at least one unknown material. This surveying may be accomplished using visible imagery or SWIR imagery. The target area may be interrogated using Raman spectroscopy and LIBS spectroscopy to identify the unknown material. SWIR techniques may also be used to interrogate the target area. Fusion algorithms may also be applied to visible images, SWIR data sets, Raman data sets, and/or LIBS data sets.

Claims

1. A system comprising:

a first illumination source configured to illuminate a target area comprising an unknown material, to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said material, photons scattered by said material, photons plasma emitted by said material, and combinations thereof;

a first optical system coupled to said laser light source to direct light to the target area;

a video capture device that outputs a dynamic image of said target area;

a first two-dimensional array of detection elements;

a second optical system that collects at least one of said reflected photons, said scattered photons, and said plasma emitted photons, and

directs the collected reflected photons to said first two-dimensional array of detection elements, wherein said first two-dimensional array of detection elements is coupled to said second optical system, and

further directs at least one of said scattered photons and said plasma emitted photons to a fiber array spectral translator device, wherein said fiber array spectral translator device is coupled to said second optical system;

wherein said first two-dimensional array detects in a spatially accurate manner said reflected photons received from said second optical system to thereby generate at least one of;

a plurality of spatially accurate wavelength resolved short wave infrared images and a plurality of spatially resolved short wave infrared spectra;

wherein said fiber array spectral translator device outputs at least one of the following received from said second optical system;

said collected scattered photons, and said collected plasma emitted photons, and includes a two-dimensional array of optical fibers drawn into a one-dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;

at least one spectrometer coupled to said one-dimensional fiber stack of said fiber array spectral translator device, wherein an entrance slit of said spectrometer is coupled to said one dimensional fiber stack to perform at least one of the following;

disperse said scattered photons output by said fiber array spectral translator device to generate a plurality of spatially resolved Raman spectra, and disperse said plasma emitted photons output by said fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra; and

wherein said second two dimensional array of detection elements coupled to said spectrograph detects at least one of;

said plurality of spatially resolved Raman spectra, said plurality of spatially resolved atomic spectra, and combinations thereof.

2. The system of claim 1 wherein said second two dimensional array of detection elements comprises at least one of:

a Raman detector and a LIBS detector.

3. The system of claim 2 further comprising:

a Raman spectrograph configured to disperse said scattered photons output by said fiber array spectral translator device to generate a plurality of spatially resolved Raman spectra;

said Raman detector configured to detect said spatially resolved Raman spectra;

a LIBS spectrograph configured to disperse said plasma emitted photons output by said fiber array spectral translator device to generate a plurality of spatially resolved atomic spectra; and

said LIBS detector configured to detect said spatially resolved atomic spectra.

4. The system of claim 1 wherein said first illumination source comprises at least one of:

a laser light source, a broadband light source, an ambient light source, and combinations thereof.

5. The system of claim 1 wherein said illumination source illuminates said target area using at least one of:

continuous wave excitation, pulsed laser excitation, and combinations thereof.

6. The system of claim 1 wherein said first illumination source illuminates said target area using structured illumination.

7. The system of claim 6 wherein said structured illumination is configured so as to provide for simultaneous acquisition of short wave infrared spectral data, Raman spectral data, and LIBS spectral data.

8. The system of claim 1 wherein said illumination source illuminates a region of said target area with a first wavelength to produce said scattered photons and a region of said target area with a second wavelength to produce said plasma emitted photons.

9. The system of claim 1 wherein said illumination source is configured for illumination in a plurality of modes, wherein each mode comprises illuminating using a different excitation wavelength.

10. The system of claim 1 wherein said first optical system further comprises a telescope to locate and focus on said target area, said telescope coupled to said first optical system.

11. The system of claim 10 wherein said first optical system further comprises a collection lens.

12. The system of claim 10 wherein said first optical system further comprises a plurality of collection lenses.

13. The system of claim 1 further comprising:

a Raman spectrometer for receiving said dispersed Raman photons,

a Raman detector for receiving at least one of said plurality of spatially resolved Raman spectra and said plurality of spatially resolved Raman images,

a libs spectrometer for receiving said dispersed atomic emitted photons, and

a LIBS detector for receiving at least one of said plurality of spatially resolved LIBS spectra and said plurality of spatially resolved LIBS images.

14. The system of claim 1 further comprising a tunable filter.

15. The system of claim 14 wherein said tunable filter is selected from the group consisting of:

a liquid crystal tunable filter, a multi-conjugate liquid crystal tunable filter, a short wave infrared multi-conjugate liquid crystal tunable filter, acousto-optical tunable filter, a electro-optical tunable filter, and combinations thereof.

16. The system of claim 1 further comprising instructions executable by at least one processor that apply a fusion algorithm to two or more of the following:

said plurality of spatially resolved short wave infrared spectra, said plurality of spatially resolved atomic spectra, and said spatially resolved Raman spectra, to thereby identify said unknown material.

17. The system of claim 1 further comprising at least one processor configured to generate a plurality of control signals, wherein said control signals include:

first control signals that control operation of at least one of said first illumination source and said telescope;

second control signals that control operation of said second optical system such that the second optical system directs the collected reflected photons to a tunable filter and directs the collected scattered photons and the plasma emitted photons to said fiber array spectral translator device; and

third control signals that control operation of the tunable filter such that the tunable filter sequentially filters collected reflected photons in each of a plurality of predetermined wavelength bands.

18. The system of claim 1 further comprising a means for engaging laser interlocking in response to detecting at least one human present in at least one of a region of interest and a target area.

19. The system of claim 1 wherein said video capture device is configured to operate in a targeting mode to thereby locate said target area.

20. The system of claim 19 wherein said target area is located based on at least one of:

size of said target area, shape of said target area, color of said target area, and combinations thereof.

21. The system of claim 1 further comprising a second illumination source for illuminating said target area to thereby generate a second plurality of interacted photons wherein said second plurality of interacted photons are selected from the group consisting of:

photons reflected by said material, photons scattered by said material, photons plasma emitted by said material, and combinations thereof.

22. The system of claim 21 wherein said laser light source is selected from the group consisting of:

a laser light source, a broadband light source, an ambient light source, and combinations thereof.

23. The system of claim 1 further comprising a means for configuring gated detection of at least one of:

said reflected photons, said scattered photons, said plasma emitted photons, and combinations thereof.

24. The system of claim 1 wherein said unknown material comprises at least one of:

a chemical threat agent, a biological threat agent, an explosive threat agent, a non-threat agent, a material associated with a threat agent, and combinations thereof.

25. A method comprising:

illuminating a region of interest comprising a target area to thereby generate a first plurality of interacted photons from said region of interest wherein said first plurality of interacted photons comprise photons reflected by said region of interest;

assessing said reflected photons to thereby generate at least one SWIR data set representative of said region of interest;

analyzing said SWIR data set to identify a target area within said region of interest;

illuminating said target area wherein said target area comprises an unknown material to thereby produce a second plurality of interacted photons wherein said second plurality of interacted photons are selected from the group consisting of;

a plurality of photons scattered by said material and a plurality of photons plasma emitted by said material;

collecting, via a fiber array spectral translator device, at least one of said scattered photons and said plasma emitted photons, wherein said fiber array spectral translator device comprises a two dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view;

assessing said scattered photons using Raman spectroscopy to thereby generate at least one Raman data set representative of said target area; and

assessing said plasma emitted photons using laser induced breakdown spectroscopy to thereby generate at least one LIBS data set representative of said target area.

26. The method of claim 25 wherein said SWIR data set comprises at least one of:

a plurality of spatially resolved SWIR spectra and a plurality of spatially resolved SWIR images.

27. The method of claim 25 wherein said SWIR data set comprises a SWIR hyperspectral image.

28. The method of claim 25 wherein said SWIR data set comprises a dynamic chemical image.

29. The method of claim 25 wherein said Raman data set comprises at least one of:

a plurality of spatially resolved Raman spectra and a plurality of spatially resolved Raman images.

30. The method of claim 25 wherein said Raman data set comprises a Raman hyperspectral image.

31. The method of claim 25 wherein said Raman data set comprises a dynamic chemical image.

32. The method of claim 25 wherein said LIBS data set comprises at least one of:

a plurality of spatially resolved atomic spectra and a plurality of spatially resolved LIBS images.

33. The method of claim 25 wherein said LIBS data set comprises a LIBS hyperspectral image.

34. The method of claim 25 wherein said LIBS data set comprises a LIBS chemical image.

35. The method of claim 25 further comprising applying a fusion algorithm to at least two of the following to identify one or more unknown materials in said target area:

a visible image representative of a region of interest, said Raman data set and said LIBS data set.

36. The method of claim 25 further comprising surveying at least one of said region of interest and said target area using a video capture device.

37. The method of claim 25 wherein said illuminating of said target area is achieved using structured illumination.

38. The method of claim 25 wherein at least one of said region of interest and said target area are illuminated using at least one of continuous wave excitation, pulsed laser excitation, and combinations thereof.

39. The method of claim 25 wherein at least one of said reflected photons, said scattered photons, and said plasma emitted photons are analyzed using gated detection.

40. The method of claim 37 wherein said structured illumination comprises:

illuminating a first region of said target area with a first illumination pattern and illuminating a second region of said target area with a second illumination pattern.

41. The method of claim 40 wherein said first region of said target area is illuminated using a first excitation wavelength and said second region of said target area is illuminated using a second excitation wavelength.

42. The method of claim 40 wherein said first region of said target area and said second region of said target area are illuminated sequentially.

43. The method of claim 40 wherein said first region of said target area and said second region of said target area are illuminated simultaneously.

44. The method of claim 25 wherein said region of interest is illuminated using at least one of:

an ambient light source, a broadband light source, and a laser light source.

45. The method of claim 25 wherein said illumination of at least one of said region of interest and said target area is configured so as to engage laser interlocking in response to detecting at least one human present in at least one of a region of interest and a target area.

46. The method of claim 25 wherein said unknown material comprises at least one of:

a chemical threat agent, a biological threat agent, an explosive threat agent, a non-threat agent, a material associated with a threat agent, and combinations thereof.

54. The method of claim 46 wherein said region of interest is illuminated using a light source selected from the group consisting of:

a laser light source, a broadband light source, an ambient light source, and combinations thereof.

55. The method of claim 46 wherein said target area is illuminated using a light source selected from the group consisting of:

a laser light source, a broadband light source, an ambient light source, and combinations thereof.

56. The method of claim 46 wherein said illumination of at least one of said region of interest and said target area is configured so as to engage laser interlocking when human motion is detected.

57. The method of claim 46 wherein said unknown material comprises at least one of:

a chemical threat agent, a biological threat agent, an explosive threat agent, a non-threat agent, a material associated with a threat agent, and combinations thereof.

47. A method comprising:

surveying a region of interest using a video capture device to thereby indentify a target area in said region of interest;

illuminating said target area, wherein said target area comprises an unknown material, to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said material, photons scattered by said material, photons plasma emitted by said material, and combinations thereof;

assessing said reflected photons using SWIR spectroscopy to thereby generate at least one SWIR data set representative of said target area;

assessing said scattered photons using Raman spectroscopy to thereby generate at least one Raman data set;

assessing said plasma emitted photons to thereby generate at least one LIBS data set;

applying a fusion algorithm to at least two of the following to identify one or more unknown materials in said target area;

a visible image representative of a region of interest, said SWIR data set, said Raman data set, and said LIBS data set.

48. The method of claim 47 further comprising collecting at least one of said reflected photons, said scattered photons, and said plasma emitted photons via a fiber array spectral translator device, wherein said device comprises a two-dimensional non-linear array of optical fibers drawn into a one dimensional fiber stack so as to effectively convert a two-dimensional field of view into a curvilinear field of view.

49. The method of claim 47 wherein said target area is illuminated using structured illumination.

50. The method of claim 47 wherein said target area is illuminated using at least one of continuous laser excitation, pulsed laser excitation, and combinations thereof.

51. The method of claim 47 wherein at least one of said reflected photons, said scattered photons, and said plasma emitted photons are analyzed using gated detection.

52. The method of claim 47 further comprising passing at least one of said reflected photons, said scattered photons, and said plasma emitted photons through a tunable filter.

53. The method of claim 51 wherein said tunable filter is selected from the group consisting of:

a liquid crystal tunable filter, a multi-conjugate liquid crystal tunable filter, a short wave infrared multi-conjugate liquid crystal tunable filter, acousto-optical tunable filter, a electro-optical tunable filter, and combinations thereof.