Method and apparatus for conducting Raman spectroscopy

• US 20050248759A1
• Filed: 04/29/2005
• Published: 11/10/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Ahura Scientific, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Ahura Scientific, Inc. (Thermo Fisher Scientific Incorporated)
• Inventors: Azimi, Masud, Knopp, Kevin J., Wang, Peidong, Vakhshoori, Daryoosh, Shen, Yu
• Granted Patent: US 7,636,157 B2
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/656 Raman microprobe
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

In another form of the present invention, there is provided a Raman probe comprising: a first optical fiber for receiving laser excitation light from a light source and transmitting the same; a first filter for receiving light from the first optical fiber and adapted to pass the laser excitation light and to block spurious signals associated with the light; a second filter for receiving light from the first filter and adapted to direct the light toward the specimen; focusing apparatus for receiving the light from the second filter, focusing the light on a specimen so as to generate the Raman signal, and returning the Raman signal to the second filter; wherein the second filter is further configured so that when the second filter receives the Raman signal from the focusing apparatus, the second filter filters out unwanted laser excitation light before directing the Raman signal to a second optical fiber; and a second optical fiber for receiving the Raman signal from the second filter and transmitting the same to a light analyzer. In another form of the present invention, there is provided a Raman probe comprising: a light source for generating laser excitation light; focusing apparatus for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and a light analyzer for analyzing the Raman signature of the specimen, whereby to identify the specimen; wherein the focusing apparatus is configured to permit the specimen to reside in a vial receptacle or at a target location remote from the vial receptacle. In another form of the present invention, there is provided a method for conducting Raman spectroscopy of a specimen, comprising: generating laser excitation light using a light source; passing the laser excitation light through a first filter so as to block spurious signals associated with the light; passing the laser excitation light through a second filter so as to direct the light toward the specimen; receiving the light from the second filter, focusing the light on a specimen so as to generate the Raman signal, and returning the Raman signal to the second filter; wherein the second filter is further configured so that when the second filter receives the Raman signal from the specimen, the second filter filters out unwanted laser excitation light; passing the filtered light received from the second filter to a light analyzer; and analyzing the Raman signature of the specimen so as to identify the specimen. In another form of the present invention, there is provided a Raman probe comprising: a housing; a light source disposed within the housing for generating laser excitation light; focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen; wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing; and further comprising an optical shield mounted to the housing so as to be disposed between the specimen and the user, whereby to optically shield the user from the light source. In another form of the present invention, there is provided a Raman probe comprising: a housing; a light source disposed within the housing for generating laser excitation light; focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen; wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing; and further comprising a camera mounted to the housing so that its field of view encompasses the target location, and a display mounted to the housing for displaying the image captured by the camera, whereby to permit the user to position the probe relative to the specimen while watching the display.

Claims

1. A Raman probe comprising:

a first optical fiber for receiving laser excitation light from a light source and transmitting the same;

a first filter for receiving light from the first optical fiber and adapted to pass the laser excitation light and to block spurious signals associated with the light;

a second filter for receiving light from the first filter and adapted to direct the light toward a specimen;

focusing apparatus for receiving the light from the second filter, focusing the light on the specimen so as to generate the Raman signal, and returning the Raman signal to the second filter;

wherein the second filter is further configured so that when the second filter receives the Raman signal from the focusing apparatus, the second filter filters out unwanted laser excitation light before directing the Raman signal to a second optical fiber; and

a second optical fiber for receiving the Raman signal from the second filter and transmitting the same to a light analyzer.

2. A Raman probe according to claim 1 further comprising a light source.

3. A Raman probe according to claim 2 wherein the light source comprises at least one 785 nm semiconductor laser with limited linewidth.

4. A Raman probe according to claim 3 wherein the light source has a linewidth <

0.2 nm FWHM.

5. A Raman probe according to claim 1 further comprising a lens disposed between the first fiber and the first filter for collimating light from the first fiber on the first filter.

6. A Raman probe according to claim 1 wherein the spurious signals associated with the light comprise spurious signals associated with the laser, the fiber, and/or both.

7. A Raman probe according to claim 6 wherein the spurious signals associated with the laser comprise ASE.

8. A Raman probe according to claim 1 wherein the spurious signals associated with the light comprise spurious signals associated with the fiber.

9. A Raman probe according to claim 8 wherein spurious signals associated with the fiber comprise fluorescence.

10. A Raman probe according to claim 8 wherein the spurious signals associated with the fiber comprise Raleigh and Raman scatterings.

11. A Raman probe according to claim 1 wherein the spurious signals associated with the light comprise spurious signals associated with both the laser and the fiber.

12. A Raman probe according to claim 1 wherein the first filter is adapted to block ASE from the laser and fluorescence and Raleigh and Raman scatterings generated inside the first fiber.

13. A Raman probe according to claim 1 wherein the first filter comprises a bandpass filter.

14. A Raman probe according to claim 13 wherein the bandpass filter comprises a plurality of bandpass filter units working in combination with one another.

15. A Raman probe according to claim 1 wherein the first filter is adapted to filter out ASE background in the Raman domain of >

300 cm−

1.

16. A Raman probe according to claim 1 wherein the second filter comprises a plurality of filter units working in combination with one another.

17. A Raman probe according to claim 16 wherein the second filter comprises three or more filter units working in combination with one another.

18. A Raman probe according to claim 1 wherein the second filter comprises a filter unit working in combination with a reflector unit.

19. A Raman probe according to claim 1 wherein the second filter is configured at a 22.5 degree Angle of Optical Incidence (AOI).

20. A Raman probe according to claim 1 wherein the second filter is configured at a 5 degree Angle of Optical Incidence (AOI).

21. A Raman probe according to claim 1 wherein the second filter is configured at a 10 degree Angle of Optical Incidence (AOI).

22. A Raman probe according to claim 1 wherein the second filter comprises a long-pass filter.

23. A Raman probe according to claim 22 wherein the long-pass filter is adapted to filter out the ASE background in the Raman domain of >

300 cm−

1.

24. A Raman probe according to claim 22 wherein the long-pass filter comprises a plurality of long-pass filter units working in combination with one another.

25. A Raman probe according to claim 24 wherein the long-pass filter comprises three or more long-pass filter units working in combination with one another.

26. A Raman probe according to claim 22 wherein the long-pass filter comprises a long-pass filter unit working in combination with a reflector unit.

27. A Raman probe according to claim 1 wherein the focusing apparatus comprises a lens disposed between the second filter and the specimen.

28. A Raman probe according to claim 1 wherein the focusing apparatus comprises a first lens for receiving light from the second filter, a vial receptacle for receiving light from the first lens, a second lens for receiving light from the vial receptacle, a third lens for receiving light from the second lens and focusing that light on a target location, whereby the focusing apparatus is adapted so that (i) when a specimen is located in the vial receptacle, focus light on the specimen, and (ii) when no specimen is located vial receptacle, focus light on the target location.

29. A Raman probe according to claim 28 wherein the first lens, vial receptacle, second lens, third lens and target location are all aligned with one another.

30. A Raman probe according to claim 1 wherein the second filter is adapted to provide up to >

OD10 filtration of the laser excitation light before directing the Raman signal to a second optical fiber.

31. A Raman probe according to claim 1 wherein a broadband reflector is disposed between second filter and the second fiber.

32. A Raman probe according to claim 31 wherein the broadband reflector is adapted to provide up to OD1 filtering of the laser excitation light before directing the Raman signal to a second optical fiber.

33. A Raman probe according to claim 31 wherein the broadband reflector reflects Raman signal and passes laser excitation light.

34. A Raman probe according to claim 31 wherein the broadband reflector reflects Raman signal of >

300 cm−

1, and passes Raman signal of 0 to 300 cm−

1.

35. A Raman probe according to claim 31 wherein the broadband reflector is configured at a 45 degree Angle of Optical Incidence (AOI).

36. A Raman probe according to claim 1 further comprising a lens disposed between the second filter and the second fiber.

37. A Raman probe according to claim 1 further comprising a light analyzer.

38. A Raman probe according to claim 37 wherein the light analyzer comprises a spectrometer.

39. A Raman probe according to claim 37 wherein the light analyzer comprises a spectrometer and associated analysis apparatus adapted to analyze the Raman signature of the specimen, whereby to identify the specimen.

40. A Raman probe comprising:

a light source for generating laser excitation light;

focusing apparatus for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and

a light analyzer for analyzing the Raman signature of the specimen, whereby to identify the specimen;

wherein the focusing apparatus is configured to permit the specimen to reside in a vial receptacle or at a target location remote from the vial receptacle.

41. A Raman probe according to claim 40 wherein the vial receptacle and the target location are aligned with one another.

42. A Raman probe according to claim 40 wherein the focusing apparatus comprises a first lens for receiving light from the light source, a vial receptacle for receiving light from the first lens, a second lens for receiving light from the vial receptacle, a third lens for receiving light from the second lens and focusing that light on a target location, whereby the focusing apparatus is adapted so that (i) when a specimen is located in the vial receptacle, focus light on the specimen, and (ii) when no specimen is located vial receptacle, focus light on the target location.

43. A Raman probe according to claim 42 wherein the first lens, vial receptacle, second lens, third lens and target location are all aligned with one another.

44. A Raman probe according to claim 42 further comprising a vial adapted to be seated in the vial receptacle.

45. A Raman probe according to claim 42 wherein the vial further comprises a shutter for preventing stray backlight from entering the vial receptacle when the vial is disposed in the vial receptacle.

46. A Raman probe according to claim 40 wherein the focusing apparatus comprises a conical standoff located between the vial receptacle and the target location.

47. A Raman probe according to claim 46 wherein the conical standoff comprises a window located between the vial receptacle and the target location.

48. A Raman probe according to claim 46 wherein the conical standoff is removably connected to the remainder of the probe.

49. A Raman probe according to claim 46 wherein the conical standoff is pivotally connected to the remainder of the probe.

50. A method for conducting Raman spectroscopy of a specimen, comprising:

generating laser excitation light using a light source;

passing the laser excitation light through a first filter so as to block spurious signals associated with the light;

directing the laser excitation light to a second filter so as to direct the laser excitation light toward the specimen;

receiving the light from the second filter, focusing the light on the specimen so as to generate the Raman signal, and returning the Raman signal to the second filter;

wherein the second filter is further configured so that when the second filter receives the Raman signal from the specimen, the second filter filters out unwanted laser excitation light;

passing the filtered light received from the second filter to a light analyzer; and

analyzing the Raman signature of the specimen so as to identify the specimen.

51. A Raman probe comprising:

a housing;

a light source disposed within the housing for generating laser excitation light;

focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and

a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen;

wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing;

and further comprising an optical shield mounted to the housing so as to be disposed between the specimen and the user, whereby to optically shield the user from the light source.

52. A Raman probe according to claim 51 wherein the optical shield is adapted to block the operative wavelength of the light source.

53. A Raman probe according to claim 51 wherein the optical shield has a semi-circular configuration.

54. A Raman probe comprising:

a housing;

a light source disposed within the housing for generating laser excitation light;

focusing apparatus disposed within the housing for receiving the laser excitation light from the light source, focusing the laser excitation light on a specimen so as to generate the Raman signal, and returning the Raman signal to a light analyzer; and

a light analyzer disposed within the housing for analyzing the Raman signature of the specimen, whereby to identify the specimen;

wherein the focusing apparatus is configured to permit the specimen to reside at a target location remote from the housing;

and further comprising a camera mounted to the housing so that its field of view encompasses the target location, and a display mounted to the housing for displaying the image captured by the camera, whereby to permit the user to position the probe relative to the specimen while watching the display.