System and method for instrument response correction based on independent measurement of the sample

• US 8,537,354 B2
• Filed: 02/11/2011
• Issued: 09/17/2013
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Maier, John, Fuhrman, Michael
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Nur, Abdullahi
• Application Number:
  US12/931,868
• Publication Number:
  US 20110211763A1
• Time in Patent Office: 949 Days
• Field of Search: 356 72- 73, 356/301, 356/300, 356/326, 356/328, 356/334
• US Class Current: 356/301
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0297 Constructional arrangements for removing other types of optical noise or for performing calibration
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/276 with alternation of sample and standard in optical path
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 2201/1293 resolving multicomponent spectra

Abstract

A system and method for providing an instrument response correction. A sample is illuminated to generate a first plurality and a second plurality of interacted photons. The first plurality of interacted photons may be detected by a dispersive spectrometer to generate a reference spectrum representative of the sample. The second plurality of interacted photons may be passed through a tunable filter and detected using an imaging detector to generate at least one hyperspectral image. This hyperspectral image may comprise a Raman hyperspectral image or an infrared hyperspectral image. A system may comprise an illumination source, a collection optics, a dispersive spectrometer, a fiber optic, a tunable filter, and an imaging detector.

Claims

1. A method comprising:

illuminating a sample to thereby generate a first plurality of interacted photons and a second plurality of interacted photons;

detecting said first plurality of interacted photons using a dispersive spectrometer to thereby generate at least one reference spectrum representative of said sample;

passing said second plurality of interacted photons through a tunable filter;

detecting said second plurality of interacted photons using an imaging detector to thereby generate at least one hyperspectral test image representative of said sample;

assessing said test image to thereby determine a mean test spectrum wherein said mean test spectrum is representative of the mean intensity of a plurality of pixels in said hyperspectral test image;

comparing said mean test spectrum to said reference spectrum to thereby determine an instrument response correction; and

applying said instrument response correction to said hyperspectral test image.

2. The method of claim 1 further comprising masking said test image so as to:

include a first plurality of pixels wherein said first portion of pixels comprise pixels sampled by said dispersive spectrometer, and exclude a second plurality of pixels wherein said second portion of pixels comprise pixels not sampled by said dispersive spectrometer.

3. The method of claim 1 further comprising:

obtaining a plurality of reference spectra representative of said sample via said dispersive spectrometer, and assessing said plurality of reference spectra to thereby determine a mean reference spectrum representative of said sample.

4. The method of claim 1 wherein said first plurality of interacted photons and said second plurality of interacted photons are detected substantially simultaneously.

5. The method of claim 1 wherein said first plurality of interacted photons and said second plurality of interacted photons are detected sequentially.

6. The method of claim 1 wherein application of said instrument response correction results in an adjusted mean test spectrum associated with said test image, wherein said adjusted mean test spectrum is substantially equal to said reference spectrum.

7. The method of claim 1 wherein at least one of said first plurality of interacted photons and said second plurality of interacted photons are selected from the group consisting of:

photons scattered by said sample, photons reflected by said sample, photons absorbed by said sample, photons emitted by said sample, and combinations thereof.

8. The method of claim 1 wherein said reference spectrum comprises at least one Raman spectra.

9. The method of claim 1 wherein said reference spectrum comprises at least one of:

a short wave infrared spectra, a near infrared spectra, a mid wave infrared spectra, a long wave infrared spectra, and combinations thereof.

10. The method of claim 1 wherein said sample comprises a biological sample.

11. The method of claim 1 wherein said sample comprises a chemical sample.

12. The method of claim 1 wherein said sample comprises an explosive agent.

13. The method of claim 1 wherein said first plurality of interacted photons are transmitted to said dispersive spectrometer via at least one fiber optic.

14. The method of claim 13 wherein said at least one fiber optic comprises a fiber array spectral translator device.

15. The method of claim 1 wherein said comparing is achieved by applying at least one chemometric technique.

16. The method of claim 1 wherein said hyperspectral test image comprises at least one Raman hyperspectral image.

17. The method of claim 1 wherein said hyperspectral test image comprises a hyperspectral image selected from the group consisting of:

a short wave infrared hyperspectral image, a near infrared hyperspectral image, a mid wave infrared hyperspectral image, a long wave infrared hyperspectral image, and combinations thereof.

18. A system comprising:

an illumination source for illuminating a sample to thereby generate a first plurality of interacted photons and a second plurality of interacted photons;

a collection optics for collecting at least one of said first plurality of interacted photons and said second plurality of interacted photons;

a dispersive spectrometer for detecting said first plurality of interacted photons and generating at least one reference spectrum representative of said sample;

at least one fiber optic, wherein a first end of said fiber optic is coupled to said collection optics and said second end is coupled to an entrance slit of said dispersive spectrometer;

a tunable filter for sequentially filtering said second plurality of interacted photons into a plurality of predetermined wavelength bands;

an imaging detector configured so as to detect said second plurality of interacted photons to thereby generate at least one hyperspectral test image representative of said sample; and

at least one processor configured to assess the hyperspectral test image and generate at least one mean test spectra and compare the hyperspectral test image with the reference spectrum.

19. The system of claim 18 further comprising a platform configured to hold said sample.

20. The system of claim 18 wherein said tunable filter comprises a filter selected from the group consisting of:

a liquid crystal tunable filter, a multi-conjugate liquid crystal tunable filter, and combinations thereof.

21. The system of claim 18 wherein said imaging detector comprises a Raman hyperspectral imaging detector.

22. The system of claim 18 wherein said imaging detector comprises a hyperspectral imaging detector selected from the group consisting of:

a short wave infrared hyperspectral imaging detector, a near infrared hyperspectral imaging detector, a mid wave hyperspectral imaging detector, a long wave hyperspectral imaging detector, and combinations thereof.

23. The system of claim 18 wherein said at least one fiber optic comprises a fiber array spectral translator device.

24. The system of claim 18 further comprising a non-transitory storage medium containing machine readable program code, which, when executed by a processor, causes said processor to perform the following:

generate a mean spectrum representative of said hyperspectral test image;

compare said mean spectrum to said reference spectra;

determine an instrument response correction; and

apply said instrument response correction to said hyperspectral test image.

25. A non-transitory data storage medium containing program code, which, when executed by a processor causes said processor to perform the following:

illuminate a sample to thereby generate a first plurality of interacted photons and a second plurality of interacted photons;

detect said first plurality of interacted photons using a dispersive spectrometer to thereby generate at least one reference spectrum representative of said sample;

pass said second plurality of interacted photons through a tunable filter;

detect said second plurality of interacted photons using an imaging detector to thereby generate at least one hyperspectral test image representative of said sample;

assess said test image to thereby determine a mean test spectrum wherein said mean test spectrum is representative of the mean of the intensity at each pixel in said hyperspectral test image;

compare said mean test spectrum to said reference spectrum to thereby determine an instrument response correction; and

apply said instrument response correction to said hyperspectral test image.

26. The non-transitory data storage medium of claim 25 which, when executed by a processor further causes said processor to perform the following:

obtain a plurality of reference spectra representative of said sample via said dispersive spectrometer, and assess said plurality of reference spectra to thereby determine a mean reference spectra representative of said sample.

27. The non-transitory data storage medium of claim 25 which, when executed by a processor further causes said processor to mask said test image so as to:

include a first plurality of pixels wherein said first portion of pixels comprise pixels sampled by said dispersive spectrometer, and exclude a second plurality of pixels wherein said second portion of pixels comprise pixels not sampled by said dispersive spectrometer.