Method and apparatus for compact Fabry-Perot imaging spectrometer

• US 20050030545A1
• Filed: 07/19/2004
• Published: 02/10/2005
• Est. Priority Date: 07/18/2003
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Wang, Chenhui, Tuschel, David, Treado, Patrick J.
• Granted Patent: US 6,985,233 B2
• Time in Patent Office: Days
• US Class Current: 356/454
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0224 using polarising or depolarising elements
• 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 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0283 using a charging unit
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01J 3/4406 Fluorescence spectrometry
• CPC Class Codes: G01N 2021/6417 Spectrofluorimetric devices
• CPC Class Codes: G01N 2021/6423 Spectral mapping, video display
• CPC Class Codes: G01N 2021/6471 Special filters, filter wheel
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held
• CPC Class Codes: G01N 2201/0627 Use of several LED's for spectral resolution
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells

Abstract

The disclosure generally relates to a method and apparatus for compact Fabry-Perot imaging spectrometer. More specifically, in one embodiment, the disclosure concerns a tunable Fabry-Perot optical filter for providing a spatially accurate wavelength-resolved image of a sample having two spatial dimensions. The optical filter may include plural filter elements having an initial predetermined spacing between adjacent filter elements; and a micro electromechanical system (“MEMS”) actuator. One of the plural filter elements may be attached to the MEMS actuator so that the actuator is capable of moving said one filter element relative to another of said plural filter elements to thereby tune said Fabry-Perot optical filter.

Claims

1. A tunable Fabry-Perot optical filter for providing a spatially accurate wavelength-resolved image of a sample having two spatial dimensions comprising:

plural filter elements having an initial predetermined spacing between adjacent filter elements; and

a micro electromechanical system (“

MEMS”

) actuator,

wherein one of said plural filter elements is attached to said MEMS actuator so that said MEMS actuator is capable of moving said one filter element relative to another of said plural filter elements to thereby tune said Fabry-Perot optical filter.

2. The filter of claim 1 wherein the initial predetermined spacing is uniform between each set of adjacent filter elements.

3. The filter of claim 1 wherein said filter elements are comprised of silicon.

4. The filter of claim 1 wherein said filter elements are initially positioned substantially parallel to each other.

5. The filter of claim 1 wherein said MEMS actuator is a substrate to which one of said plural filter elements is attached.

6. The filter of claim 5 wherein said one filter element comprises plural sub-elements and said substrate comprises plural MEMS sub-actuators so that a one of said sub-elements is attached to a one of said sub-actuators so that said one sub-actuator is capable of moving said one sub-element relative to another of said sub-elements.

7. The filter of claim 1 further comprising a power source for driving said MEMS actuator.

8. A method for tuning a Fabry-Perot optical filter comprising the steps of:

providing a Fabry-Perot filter having plural filter elements having an initial predetermined spacing between adjacent filter elements;

attaching one of said plural filter elements to a micro electromechanical system (“

MEMS”

) actuator; and

providing power to the MEMS actuator to thereby move said one filter element relative to another of said plural filter elements to thereby tune the Fabry-Perot optical filter.

9. The method of claim 8 wherein the MEMS actuator is a substrate to which one of the plural filter elements is attached.

10. The method of claim 9 wherein the one filter element comprises plural sub-elements and the substrate comprises plural MEMS sub-actuators so that a one of the sub-elements is attached to a one of the sub-actuators so that the step of providing power includes providing power to the one sub-actuator so as to move the one sub-element relative to another of the sub-elements.

11. A system for obtaining a spatially accurate wavelength resolved spectrum of a sample, comprising:

a photon emission source for illuminating the sample with a plurality of photons to thereby produce photons scattered by the sample;

an optical lens for collecting the scattered photons;

a first lens for directing said scattered photons;

a tunable Fabry-Perot filter for receiving the collected scattered photons and providing therefrom filtered photons; and

a second lens for directing said filtered photons;

a photon detector for receiving the filtered photons and obtaining therefrom a spectrum of the sample,

wherein said filter comprises;

plural filter elements having an initial predetermined spacing between adjacent filter elements; and

a micro electromechanical system (“

MEMS”

) actuator,

wherein one of said plural filter elements is attached to said MEMS actuator so that said MEMS actuator is capable of moving said one filter element relative to another of said plural filter elements to thereby tune said Fabry-Perot optical filter.

12. The system of claim 11 wherein said photon detector is selected from the group consisting of:

charge-coupled device, complementary metal oxide semiconductor, charge injection device, intensified charge injection device, electron multiplying charge-coupled device, silicon photo diode, silicon avalanche diode, and focal plane array.

13. The system of claim 11 wherein said photon emission source is a laser.

14. The system of claim 11 wherein said photon emission source is a light emitting diode.

15. The system of claim 14 wherein said light emitting diode is disposed as a ring.

16. The system of claim 15 wherein said light emitting diode is a plurality of light emitting diodes.

17. The system of claim 14 wherein said light emitting diode is a plurality of light emitting diodes wherein one of said plural light emitting diodes emits photons at a wavelength that is different than a wavelength of photons emitted by another of said plural light emitting diodes.

18. The system of claim 17 wherein the wavelength of photons emitted by one of said plural light emitting diodes is in the ultraviolet wavelength range.

19. The system of claim 17 wherein the wavelength of photons emitted by one of said plural light emitting diodes is in the near infrared wavelength range.

20. The system of claim 11 wherein said spectrum is obtained over a predetermined period of time and said sample is stationary during said predetermined period of time.

21. The system of claim 11 wherein said scattered photons include photons emitted by said sample.

22. The system of claim 11 wherein said spectrum is a Raman spectrum.

23. The system of claim 11 wherein said spectrum is a spatially accurate wavelength-resolved image.

24. The system of claim 11 wherein the system is portable.

25. The system of claim 11 wherein the system is hand held.

26. The system of claim 11 wherein said spectrum is obtained over a predetermined period of time and said sample is stationary during said predetermined period of time.

27. The system of claim 11 wherein said scattered photons include photons emitted by said sample.

28. The system of claim 11 wherein said filtered photons each have a wavelength within a predetermined wavelength band.

29. The system of claim 11 wherein said filter includes a polarizer.

30. The system of claim 11 wherein the initial predetermined spacing is uniform between each set of adjacent filter elements.

31. The system of claim 11 wherein said filter elements are comprised of silicon.

32. The system of claim 11 wherein said filter elements are initially positioned substantially parallel to each other.

33. The system of claim 11 wherein said MEMS actuator is a substrate to which one of said plural filter elements is attached.

34. The system of claim 33 wherein said one filter element comprises plural sub-elements and said substrate comprises plural MEMS sub-actuators so that a one of said sub-elements is attached to a one of said sub-actuators so that said one sub-actuator is capable of moving said one sub-element relative to another of said sub-elements.

35. The system of claim 11 further comprising a power source for driving said MEMS actuator.

36. A method for obtaining a spectrum of a sample, comprising:

providing a sample;

illuminating the sample with a plurality of photons to thereby produce photons scattered by the sample;

collecting the scattered photons;

providing a tunable Fabry-Perot filter;

receiving the collected scattered photons with the tunable Fabry-Perot filter and providing therefrom filtered photons; and

receiving the filtered photons with a photon detector and obtaining therefrom a spectrum of the sample.

37. The method of claim 36 wherein the step of providing the filter includes:

providing a Fabry-Perot filter having plural filter elements having an initial predetermined spacing between adjacent filter elements;

attaching one of said plural filter elements to a micro electromechanical system (“

MEMS”

) actuator; and

providing power to the MEMS actuator to thereby move said one filter element relative to another of said plural filter elements to thereby tune the Fabry-Perot optical filter.

38. The method of claim 37 wherein the MEMS actuator is a substrate to which one of the plural filter elements is attached.

39. The method of claim 38 wherein the one filter element comprises plural sub-elements and the substrate comprises plural MEMS sub-actuators so that a one of the sub-elements is attached to a one of the sub-actuators so that the step of providing power includes providing power to the one sub-actuator so as to move the one sub-element relative to another of the sub-elements.