Chemical imaging fiberscope

• US 7,551,821 B2
• Filed: 05/04/2007
• Issued: 06/23/2009
• Est. Priority Date: 07/19/1999
• Status: Expired due to Term

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Nelson, Matthew P., Keitzer, Scott A., Smith, Ryan D., Treado, Patrick J.
• Primary Examiner(s): AMARI, ALESSANDRO V
• Application Number:
  US11/744,797
• Publication Number:
  US 20070263290A1
• Time in Patent Office: 781 Days
• Field of Search: 385/115, 385/116, 385/117, 356/301, 600/160, 600/178, 600/181, 600/182
• US Class Current: 385/117
• CPC Class Codes: A61B 1/00165 with light-conductive means, e.g. fibre optics A61B1/07 takes precedence
• CPC Class Codes: A61B 1/043 for fluorescence imaging
• CPC Class Codes: A61B 1/063 for monochromatic or narrow-band illumination
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• CPC Class Codes: A61B 1/0646 with illumination filters
• CPC Class Codes: A61B 1/07 using light-conductive means, e.g. optical fibres
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0227 using notch filters
• CPC Class Codes: G01J 3/024 using means for illuminating a slit efficiently (e.g. entrance slit of a spectrometer or entrance face of fiber)
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images

Abstract

A fiberscope device is disclosed which is suitable for video imaging, laser Raman spectroscopy and laser Raman spectroscopic (i.e. chemical) imaging. The fiberscope design minimizes fiber background interference arising from the laser delivery fiber optic and the coherent fiber optic light gathering bundle while maintaining high light throughput efficiency through the use of integrated spectral filters. In the fiberscope design, the laser delivery fiber optic is offset from the coherent fiber optic light gathering bundle. The laser delivery field is captured entirely by the light gathering field of view of the coherent fiber bundle. The fiberscope incorporates spectral filter optical elements that provide environmental insensitivity, particularly to temperature and moisture. The fiberscope is suited to the analysis of a wide range of condensed phase materials (solids and liquids), including the analysis of biological materials such as breast tissue lesions and arterial plaques, in such a manner to delineate abnormal from normal tissues.

Claims

1. A method of imaging and collecting Raman spectra from a sample, the method comprising:

transmitting laser light of a specific laser excitation wavelength from a first source to a sample via one or more laser illuminating fibers;

positioning a first portion of a spectral filter between said one or more laser illumination fibers and said sample for transmitting said laser light of said specific laser excitation wavelength and rejecting light of other wavelengths;

positioning a second portion of the spectral filter between said sample and a plurality of collection fibers for transmitting wavelengths of light other than said specific laser excitation wavelength; and

receiving light scattered from said sample via said plurality of collection fibers;

wherein the spectral filter is spatially patterned into the first portion for filtering said laser light and into the second portion for transmitting light scattered or reflected by said sample to said plurality of collection fibers.

2. The method of claim 1 wherein said plurality of collection fibers are arranged in a coherent bundle.

3. The method of claim 1 wherein at least one of said first or second portions of the spectral filter exhibit environmental insensitivity to temperature and humidity.

4. The method of claim 1 further comprising positioning one or more lenses between said sample and said plurality of collection fibers.

5. The method of claim 1 wherein said first or second portions of the spectral filter are composed of a filter type selected from a group consisting of dielectric, holographic and rugate spectral filters.

6. The method of claim 1 further comprising positioning a spatial filter between said sample and said collection fibers for controlling an angular field of view of said collection fibers.

7. The method of claim 1 further comprising:

holding the distal end of a housing in proximity to said sample wherein said housing encloses said spectral filter, said one or more laser illuminating fibers, and said plurality of collection fibers;

directing the output of the collection fibers under white light illumination conditions to a live video camera via a first link;

directing the output under laser illumination conditions to a Raman spectrometer via a second link;

directing the output under laser illumination conditions to a Raman chemical imaging spectrometer and detector via a third link.

8. The method of claim 1 wherein a housing encloses said spectral filter, said one or more laser illuminating fibers and said plurality of collection fibers.

9. The method of claim 8 wherein a window is disposed at the distal end of said housing.

10. The method of claim 9 wherein said window is composed of a material selected from a group consisting of quartz, diamond and sapphire.

11. The method of claim 1 further comprising selectably transmitting white light from a second source to said sample with a plurality of white light illumination fibers.

12. The method of claim 11 wherein said plurality of collection fibers are arranged in a coherent bundle.

13. The method of claim 12 wherein at least one of said first or second portions of the spectral filter exhibit environmental insensitivity to temperature and humidity.

14. The method of claim 13 further comprising positioning one or more lenses between said sample and said plurality of collection fibers.

15. The method of claim 11 wherein a housing encloses said spectral filter, said one or more laser illuminating fibers, said plurality of white light illumination fibers and said plurality of collection fibers.

16. The method of claim 15 wherein a window is disposed at the distal end of said housing.

17. The method of claim 16 wherein said window is composed of a material selected from a group consisting of quartz, diamond and sapphire.

18. The method of claim 11 wherein said spectral filter exhibits environmental insensitivity to temperature and humidity.

19. The method of claim 11 further comprising positioning a spatial filter between said sample and said collection fibers for controlling an angular field of view of said collection fibers.

20. A method of imaging and collecting Raman spectra from a sample with a chemical imaging spectroscope, the method comprising:

transmitting laser light of a specific laser excitation wavelength from a first source to a sample via one or more laser illuminating fibers;

positioning a first portion of a spectral filter between said one or more laser illumination fibers and said sample for transmitting said laser light of said specific laser excitation wavelength and rejecting light of other wavelengths;

positioning a second portion of the spectral filter between said sample and a plurality of collection fibers for transmitting wavelengths of light other than said specific laser excitation wavelength;

positioning a spatial filter between said sample and said collection fibers for controlling an angular field of view of said collection fibers;

positioning one or more lenses between said sample and said plurality of collection fibers; and

receiving light scattered from said sample via said plurality of collection fibers;

wherein the spectral filter is spatially patterned into the first portion for filtering said laser light and into the second portion for transmitting light scattered or reflected by said sample to said plurality of collection fibers.

21. A method of illuminating and collecting light from a sample, the method comprising:

transmitting laser light of a specific laser excitation wavelength from a first source to a sample with one or more laser illuminating fibers via a first optical path;

transmitting white light from a second source to said sample with a plurality of white light illumination fibers via a second optical path;

receiving light scattered or reflected from said sample with said plurality of collection fibers;

transmitting said scattered or reflected light to an imaging apparatus via a third path;

wherein said one or more laser illumination fibers, said plurality of white light illumination fibers, said plurality of collection fibers are disposed in a housing wherein said first optical path is different from said second optical path and wherein said first and third optical paths each include a spectral filter.

22. The method of claim 21 wherein said first optical path comprises said laser illumination fibers, a first portion of a spectral filter, and a window disposed at the distal end of said housing.

23. The method of claim 22 wherein said second optical path comprises said white light illumination fibers and said window.

24. The method of claim 23 wherein said third optical path comprises said window and a second portion of said spectral filter.

25. The method of claim 24 further comprising

filtering said laser light with said first portion of the spectral filter;

wherein said first portion of said spectral filter is spatially patterned for filtering said laser light and said second portion of the spectral filter is transparent for transmitting light scattered or reflected by said sample to said collection fibers.

26. The method of claim 25 wherein said third optical path comprises said window, said second portion of said spectral filter, a spatial filter, a lens, a reflection filter, and said collection fibers.

27. The method of claim 21 wherein said first and second optical paths are each different from said third optical path.

28. The method of claim 21 wherein a first portion of said spectral filter is spatially patterned for filtering said laser light and a second portion of said spectral filter is transparent for transmitting light scattered or reflected by said sample to said collection fibers.

29. The method of claim 21 wherein said spectral filter exhibits environmental insensitivity to temperature and humidity.

30. The method of claim 21 wherein said spectral filter is composed of a filter type selected from a group consisting of dielectric, holographic and rugate spectral filters.

31. The method of claim 21 wherein said plurality of collection fibers are arranged in a coherent bundle.

32. The method of claim 21 further comprising:

disposing one or more lenses in said third optical path.

33. The method of claim 21 wherein a window is disposed at a distal end of said housing.

34. The method of claim 33 wherein said window is composed of a material selected from a group consisting of quartz, diamond and sapphire.

35. The method of claim 21 wherein said imaging apparatus comprises a spectrometer.

36. The method of claim 35 wherein said spectrometer is a Raman spectrometer.

37. The method of claim 21 wherein said imaging apparatus includes a tunable filter.

38. The method of claim 37 wherein said tunable filter is a liquid crystal tunable filter.

39. The method of claim 21 further comprising producing a Raman image of said sample.

40. The method of claim 21 further comprising producing a chemical image of said sample.

41. The method of claim 21 wherein said imaging apparatus comprises a charge-coupled device.

42. The method of claim 41 wherein said charge-coupled device is a video charge-coupled device.