METHOD AND APPARATUS FOR AUTOMATED SPECTRAL CALIBRATION

• US 20110085164A1
• Filed: 10/04/2010
• Published: 04/14/2011
• Est. Priority Date: 11/18/2008
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Nelson, Matthew, Treado, Patrick
• Granted Patent: US 8,440,959 B2
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08

Abstract

A method and apparatus for automated spectral calibration of a spectroscopy device. A method for simultaneous calibration and spectral imaging of a sample by: simultaneously illuminating the sample and a calibrant with a plurality of illuminating photons; receiving, at the spectrometer, a first plurality of photons collected from the sample and a second plurality of photons collected from the calibrant; forming a calibrant spectrum from the first plurality of collected photons and a sample spectrum from the second plurality of collected photons; comparing the calibrant spectrum with a reference spectrum of the calibrant to determine a wavelength-shift in the calibrant spectrum; applying the wavelength-shift to the sample spectrum to obtain a calibrated sample spectrum.

Claims

1. A method for simultaneous calibration and spectral imaging of a sample comprising:

simultaneously illuminating the sample and an intrinsic calibrant with a plurality of illuminating photons from a single source;

receiving, at a spectrometer, a first plurality of photons collected from the sample and a second plurality of photons collected from the calibrant;

forming a calibrant spectrum from the second plurality of collected photons and a sample spectrum from the first plurality of collected photons;

comparing the calibrant spectrum with a reference spectrum of the calibrant to determine a wavelength-shift in the calibrant spectrum; and

applying the wavelength-shift to the sample spectrum to obtain a calibrated sample spectrum.

2. The method of claim 1, wherein the photons collected from the sample are selected from the group consisting of photons reflected, refracted, emitted, scattered, transmitted and absorbed by the sample.

3. The method of claim 1, wherein the sample spectrum is one of a Raman spectrum, visible absorption spectrum, near infrared absorption spectrum, infrared absorption spectrum or fluorescence spectrum.

4. The method of claim 1, wherein the calibrant is selected from the group consisting of acetaminophen, polymethyl methacrylate, oxygen and nitrogen, neon, krypton, xenon, BK-7 glass, quartz, fused silica, naphthalene, 1,4 bis (2-methylstyryl) benzene, sulfur, toluene, acetonitrile, benzonitrile, cyclohexane, polystyrene, dysprosium oxide, and holmium oxide.

5. The method of claim 1, wherein the spectrometer is a dispersive spectrometer.

6. The method of claim 1, wherein the spectrometer is an imaging spectrometer.

7. The method of claim 6, wherein the imaging spectrometer includes at least one of:

a liquid crystal tunable filter and a multi-conjugate liquid crystal tunable filter.

8. The method of claim 1, wherein the plurality of illuminating photons have a first wavelength.

9. The method of claim 1, wherein the step of receiving the plurality of photons collected from the sample and the plurality of photons collected from the calibrant further comprises separating the photons collected from the sample from the collected from the calibrant.

10. The method of claim 1, wherein the step of receiving the plurality of photons collected from the sample and the plurality of photons collected from the calibrant further comprises filtering the received photons to remove photons of an undesired wavelength.

11. A system for simultaneous calibration and dispersive and/or spectral imaging of a sample comprising:

an input for simultaneously receiving a first plurality of photons collected from the sample and a second plurality of photons collected from an intrinsic calibrant, wherein said first plurality of photons and said second plurality of photons originate from the same source;

a spectrometer for forming a sample spectrum from the first plurality of photons and a calibrant spectrum from the second plurality of photons;

a first processor for comparing the calibrant spectrum with a reference spectrum of the calibrant to determine a wavelength-shift in the calibrant spectrum; and

a second processor for applying the wavelength-shift to the sample spectrum to obtain a calibrated sample spectrum.

12. The system of claim 11, wherein the photons collected from the sample are selected from the group consisting of photons reflected, refracted, luminesced, fluoresced, Raman scattered, transmitted, absorbed, and emitted by the sample.

13. The system of claim 11, wherein the first processor is programmed with instructions to:

a) determine a plurality of peak locations in the calibrant spectrum;

b) determine a plurality of peak locations in the reference spectrum of the calibrant;

c) compare the plurality of peak locations in the calibrant spectrum with a plurality of corresponding peak locations in the reference spectrum of the calibrant; and

d) determine the wavelength-shift as a function of the comparison between at least one peak location in the calibrant spectrum and a corresponding peak location in the reference spectrum.

14. The system of claim 11, wherein the spectrometer is a dispersive spectrometer.

15. The system of claim 11, further comprising a first medium for communicating the first plurality of photons collected from the sample and a second medium for communicating the second plurality of photons collected from the calibrant.

16. An apparatus for simultaneous calibration and dispersive and/or spectral image acquisition of a sample, comprising:

a processing circuit for simultaneously receiving a calibrant spectrum and a sample spectrum wherein the calibrant is an intrinsic calibrant and further wherein said calibrant spectrum and said sample spectrum are formed using photons from a single source; and

a memory in communication with the processing circuit, the memory storing instructions for the processing circuit to;

process the calibrant spectrum to locate and identify a plurality of peaks, compare the plurality of peak locations in the calibrant spectrum with a plurality of corresponding peak locations in a reference spectrum of the calibrant, and determine a wavelength-shift as a function of a comparison between at least one peak location in the calibrant spectrum and a corresponding peak location in the reference spectrum; and

calibrate the sample spectrum by applying the wavelength-shift to the sample spectrum.

17. The apparatus of claim 16, wherein applying the wavelength-shift further comprises:

(a) identifying a plurality of peak locations in the sample spectrum; and

(b) applying the wavelength-shift to at least one of the plurality of peak locations in the sample spectrum.

18. The apparatus of claim 16, further comprising a database for storing a reference spectrum of the calibrant.

19. The apparatus of claim 16, wherein the processing circuit comprises at least one microprocessor.

20. The apparatus of claim 16, wherein the apparatus is a spectrometer.

21. The apparatus of claim 16, wherein the sample spectrum is one of a Raman spectrum, visible absorption spectrum, near infrared absorption spectrum, infrared absorption spectrum or fluorescence spectrum.

22. The apparatus of claim 16, wherein the calibrant is selected from the group consisting of acetaminophen, polymethyl methacrylate, oxygen and nitrogen, neon, krypton, xenon, BK-7 glass, quartz, fused silica, naphthalene, 1,4 bis (2-methylstyryl) benzene, sulfur, toluene, acetonitrile, benzonitrile, cyclohexane, polystyrene, dysprosium oxide, and holmium oxide.

23. The apparatus of claim 20, wherein the spectrometer is a dispersive spectrometer.

24. The apparatus of claim 20, wherein the spectrometer is an imaging spectrometer.

25. The apparatus of claim 25, wherein the imaging spectrometer includes at least one of:

a liquid crystal tunable filter and a multi-conjugate liquid crystal tunable filter.

26. A method for simultaneous calibration and imaging of a sample in a spectrometer, the method comprising:

simultaneously illuminating the sample and an intrinsic calibrant with a plurality of illuminating photons from a single source;

receiving, at a spectrometer, a first plurality of photons collected from the sample and a second plurality of photons collected from the intrinsic calibrant;

forming a sample spectrum from the first plurality of photons and an intrinsic calibrant spectrum from the second plurality of photons;

comparing the intrinsic calibrant spectrum with a reference spectrum for said intrinsic calibrant to determine a wavelength-shift in the calibrant spectrum;

applying the wavelength-shift to the sample spectrum to obtain a calibrated sample spectrum.

27. The method of claim 26, wherein imaging defines at least one of obtaining dispersive spectral data or spectral imaging data from the sample.

28. The method of claim 26, wherein the first plurality of photons collected from the sample are selected from the group consisting of photons reflected, refracted, luminescence-emitted, fluorescence-emitted, Raman scattered, transmitted, absorbed, and emitted by the sample.

29. The method of claim 26, wherein the intrinsic calibrant is selected from the group consisting of acetaminophen, polymethyl methacrylate, oxygen and nitrogen, neon, krypton, xenon, BK-7 glass, quartz, fused silica, naphthalene, 1,4 bis (2-methylstyryl) benzene, sulfur, toluene, acetonitrile, benzonitrile, cyclohexane, polystyrene, dysprosium oxide, and holmium oxide.

30. The method of claim 26, wherein the sample spectrum is one of a Raman spectrum, near infrared absorption/reflectance spectrum, infrared absorption/reflectance spectrum, visible absorption/reflectance spectrum or fluorescence spectrum.

31. The method of claim 26, wherein the spectrometer is a dispersive spectrometer.

32. The method of claim 26, wherein the spectrometer is an imaging spectrometer.

33. The method of claim 32, wherein the imaging spectrometer includes at least one of:

a liquid crystal tunable filter and a multi-conjugate liquid crystal tunable filter.