Method and apparatus for interactive hyperspectral image subtraction

• US 7,956,991 B2
• Filed: 09/17/2008
• Issued: 06/07/2011
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Tuschel, David, Bangalore, Arjun S.
• Primary Examiner(s): LAUCHMAN, LAYLA G
• Application Number:
  US12/211,960
• Publication Number:
  US 20090066947A1
• Time in Patent Office: 993 Days
• Field of Search: 356/73, 356/317, 356/326, 356/301, 250/459.1
• US Class Current: 356/73
• CPC Class Codes: G01N 2021/178 Methods for obtaining spatial resolution of the property being measured
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

A method and apparatus of obtaining a spectral image of a plurality of predetermined chemical species. A sample is illuminated to produce photons. These photons are collected to produce a plurality of images for each predetermined chemical species, wherein each image comprises a frame consisting of a plurality of pixels. A wavelength range is identified wherein a chemical species exhibits a unique absorption of radiation. Pixels are identified that do not comprise the chemical species. The steps may be repeated for a plurality of chemical species. If more than one chemical species is present, the contribution of each in a pixel is separated and separate spectral images of each species is composed.

Claims

1. A method of obtaining a spectral image of each of a plurality of predetermined chemical species in a sample, comprising:

(a) illuminating said sample with a first plurality of photons to produce a second plurality of photons;

(b) collecting said second plurality of photons and producing a plurality of images of said sample therefrom each of said images comprising a frame consisting essentially of a plurality of pixels;

(c) for each of said plurality of predetermined chemical species, identifying at least one wavelength range at which said chemical specie exhibits a unique absorption of radiation;

(d) identifying at least one wavelength range at which none of said plurality of predetermined chemical species exhibits an absorption of radiation;

(e) in each of said image frames, identifying which of said plurality of pixels do not contain any of said plurality of predetermined chemical species;

(f) in each of said image frames, identifying which of said plurality of pixels contain only a first of said plurality of predetermined chemical species;

(g) repeating said step (f) for each of said plurality of predetermined chemical species;

(h) in each of said image frames, identifying which of said plurality of pixels contain more than one of said plurality of predetermined chemical species;

(i) for each of said plurality of pixels that contains more than one of said plurality of predetermined chemical species, separating the contribution of each of said predetermined chemical species; and

(j) composing separate spectral images of each of said plurality of predetermined chemical species in said sample.

2. The method according to claim 1, wherein said wavelength range is in the near IR range.

3. The method according to claim 1, wherein said wavelength range is in the visible range.

4. The method according to claim 1, wherein said wavelength range is in the near UV range.

5. The method according to claim 1, wherein said step (a) comprises illuminating a predetermined area of said sample with substantially monochromatic light.

6. The method according to claim 1, wherein said second plurality of photons are passed through at least one filter.

7. The method according to claim 6, wherein said at least one filter is selected from the group consisting of a tunable filter, a band pass filter, a liquid crystal tunable filter, an interferometer, an acousto optical tunable filter, a dispersive optical device and a computed tomography imaging spectrometer.

8. The method according to claim 1, wherein said spectral image is a spatially accurate wavelength resolved image.

9. The method according to claim 5, wherein said monochromatic light has a wavelength within the range of 500 nm to 800 nm.

10. The method according to claim 9, wherein said monochromatic light is produced using a laser.

11. An apparatus for obtaining a spectral image of each of a plurality of predetermined chemical species in a sample, comprising:

(a) an illumination source for illuminating said sample with a first plurality of photons to form a second plurality of photons;

(b) an optical device for receiving and directing said second plurality of photons to an imaging device;

(c) an imaging device for forming a plurality of images of said sample, each of said images comprising a frame consisting essentially of a plurality of pixels; and

(d) a processor in communication with said imaging device, said processor being adapted to;

(i) for each of said plurality of predetermined chemical species, identifying at least one wavelength range at which said chemical specie exhibits a unique absorption of radiation;

(ii) identifying at least one wavelength range at which none of said plurality of predetermined chemical species exhibits an absorption of radiation;

(iii) in each of said image frames, identifying which of said plurality of pixels do not contain any of said plurality of predetermined chemical species;

(iv) in each of said image frames, identifying which of said plurality of pixels contain only a first of said plurality of predetermined chemical species;

(v) repeating said step (iv) for each of said plurality of predetermined chemical species;

(vi) in each of said image frames, identifying which of said plurality of pixels contain more than one of said plurality of predetermined chemical species;

(vii) for each of said plurality of pixels that contains more than one of said plurality of predetermined chemical species, separating the contribution of each of said predetermined chemical species; and

(viii) composing separate spectral images of each of said plurality of predetermined chemical species in said sample.

12. The apparatus according to claim 11, wherein said wavelength range is in the near IR range.

13. The apparatus according to claim 11, wherein said wavelength range is in the visible range.

14. The apparatus according to claim 11, wherein said wavelength range is in the near UV range.

15. The apparatus according to claim 11, wherein said illumination source produces substantially monochromatic light.

16. The apparatus according to claim 11, wherein said optical device comprises at least one filter.

17. The apparatus according to claim 16, wherein said at least one filter is selected from the group consisting of a tunable filter, a band pass filter, a liquid crystal tunable filter, an interferometer, an acousto optical tunable filter, a dispersive optical device and a computed tomography imaging spectrometer.

18. The apparatus according to claim 11, wherein said spectral image is a spatially accurate wavelength resolved image.

19. The apparatus according to claim 15, wherein said monochromatic light has a wavelength within the range of 500 nm to 800 nm.

20. The apparatus according to claim 19, wherein said illumination source is a laser.