Optical Spectroscopy Utilizing Planar Spectral Filters

• US 20070091315A1
• Filed: 09/18/2006
• Published: 04/26/2007
• Est. Priority Date: 10/20/2005
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Brady, David, Gehm, Michael, McCain, Scott, Guenther, Bob
• Granted Patent: US 7,561,274 B2
• Time in Patent Office: Days
• US Class Current: 356/451
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G01J 3/1838 Holographic gratings
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector

Abstract

An optical spectrometer and/or a method of optical spectroscopy is described herein. One exemplary spectrometer includes a planar spectral filter, a dispersion system, and a detector array having at least two dimensions. The planar spectral filter filters incident light to generate a plurality of wavelength dependent spatial patterns. The dispersion system disperses the spatial patterns along at least one dimension in a wavelength dependent fashion onto the detector array. As a result, spatial patterns corresponding to different wavelengths are centered at different locations on the detector array. The dispersed spatial patterns superimpose at the detector array in an offset but overlapping relationship, creating an asymmetric image that facilitates the spectral analysis of a wide range of light sources, including diffuse or spectrally complex light sources.

Claims

1. An optical spectrometer comprising:

a planar spectral filter configured to filter incident light to generate a plurality of wavelength dependent spatial patterns;

a detector array having at least two dimensions; and

a dispersion system disposed between the filter and the detector array, said dispersion system configured to disperse the spatial patterns along at least one dimension in a wavelength dependent fashion onto the detector array.

2. The optical spectrometer of claim 1 wherein the dispersion system is configured to disperse the spatial patterns in a wavelength dependent fashion in at least two dimensions onto the detector array.

3. The optical spectrometer of claim 1 wherein the dispersion system is configured to disperse a first spatial pattern so that a center thereof is centered at a first position on the detector array, wherein the dispersion system is configured to disperse a second spatial pattern so that a center thereof is centered at a second position on the detector array, and wherein the first position is different from the second position.

4. The optical spectrometer of claim 1 wherein the dispersion system is configured to disperse first and second spatial patterns onto the detector array in an overlapping but offset relationship.

5. The optical spectrometer of claim 1 wherein the dispersion system is configured to disperse first and second spatial patterns onto the detector array such that the first and second spatial patterns superimpose in an offset relationship at the detector array.

6. The optical spectrometer of claim 1 further comprising a processor operatively connected to the detector array, said processor configured to generate spectral estimates of the incident light based on the spatial patterns dispersed onto the detector array.

7. The optical spectrometer of claim 6 wherein the processor is configured to generate the spectral estimates by:

sampling in at least one dimension the spatial patterns dispersed onto the detector array to generate a plurality of data samples; and

inverting the plurality of data samples to generate the spectral estimates of the incident light.

8. The optical spectrometer of claim 7 wherein the processor is configured to sample the spatial patterns dispersed onto the detector array in at least two dimensions to generate the plurality of data samples.

9. The optical spectrometer of claim 1 further comprising a lens system disposed between the dispersion system and the detector array, said lens system configured to image the spatial patterns onto the detector array.

10. The optical spectrometer of claim 9 wherein the lens system has a focal length and wherein the lens system is disposed one focal length away from a source of the incident light and one focal length away from the detector array.

11. The optical spectrometer of claim 1 wherein the planar spectral filter comprises one of a Fabry-Perot filter, a Fizeau interferometer, an etalon, a dichroic filter, a thin film transmission filter, a multiple film transmission filter, a thin film reflection filter, and a multiple film reflection filter.

12. An optical spectrometer comprising:

a planar spectral filter configured to filter incident light to generate a plurality of wavelength dependent spatial patterns;

a detector array having at least two dimensions;

a dispersion system disposed between the filter and the detector array, said dispersion system configured to disperse the spatial patterns in at least one dimension in a wavelength dependent fashion onto the detector array;

a lens system disposed between the dispersion system and the detector array, said lens system configured to image the spatial patterns onto the detector array; and

a processor operatively connected to the detector array, said processor configured to;

sample the spatial patterns dispersed onto the detector array in at least two dimensions to generate a plurality of data samples; and

generate spectral estimates of the incident light based on the plurality of data samples.

13. The optical spectrometer of claim 12 wherein the planar spectral filter comprises a Fabry-Perot filter.

14. The optical spectrometer of claim 12 wherein the lens system comprises a Fourier transform lens system.

15. A method of processing incident light comprising:

spectrally filtering the incident light with a planar spectral filter to generate a plurality of wavelength dependent spatial patterns; and

dispersing the filtered light to disperse the spatial patterns in at least one dimension in a wavelength dependent fashion onto a detector array having at least two dimensions.

16. The method of claim 15 wherein dispersing the filtered light comprises dispersing the filtered light in a wavelength dependent fashion in at least two dimensions onto the detector array.

17. The method of claim 15 wherein dispersing the filtered light comprises dispersing a first spatial pattern so that a center thereof is centered at a first position on the detector array and dispersing a second spatial pattern so that center thereof is centered at a second position on the detector array different from the first position.

18. The method of claim 15 further comprising processing output signals provided by the detector array to generate spectral estimates of the incident light based on the spatial patters dispersed onto the detector array.

19. The method of claim 18 wherein processing the output signals comprises:

sampling in at least one dimension the spatial patterns dispersed onto the detector array to generate a plurality of data samples; and

inverting the plurality of data samples to generate the spectral estimates of the incident light.

20. The method of claim 19 wherein sampling the spatial patterns comprises sampling in at least two dimensions the spatial patterns dispersed onto the detector array to generate the plurality of data samples.

21. The method of claim 15 further comprising providing the incident light from a diffuse source.

22. The method of claim 21 wherein the diffuse source comprises an illuminated biological sample.

23. The method of claim 15 wherein spectrally filtering the incident light comprises spectrally filtering the incident light with one of a Fabry-Perot filter, a Fizeau interferometer, an etalon, a dichroic filter, a thin film transmission filter, a multiple film transmission filter, a thin film reflection filter, and a multiple film reflection filter.