Enhancing Selectivity and/or Sensitivity of Spectroscopic Measurements in Media

• US 20070285655A1
• Filed: 04/26/2007
• Published: 12/13/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Redox Biomedical, Inc.
• Original Assignee: C8 MediSensors, Inc.
• Inventors: Lipson, Jan, McNamara, Robert P., Lipson, Albert L.
• Granted Patent: US 7,742,166 B2
• Time in Patent Office: Days
• US Class Current: 356/300
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/0289 Field-of-view determination; Aiming or pointing of a spectrometer; Adjusting alignment; Encoding angular position; Size of measurement area; Position tracking
• CPC Class Codes: G01N 2021/4709 Backscatter
• CPC Class Codes: G01N 2021/4747 Concentric bundles
• CPC Class Codes: G01N 2021/656 Raman microprobe
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 2201/124 Sensitivity

Abstract

An apparatus for enhancing the selectivity for spectroscopic measurements of analytes in a turbid medium is described. In one example, spatial filters are used to select only certain radii from the medium to be imaged. This selection is accomplished by placing an optical obstruction on the surface of the medium or at an image plane of the surface later in the optical imaging system. In one implementation, this is achieved by placing a fiber bundle at an image plane of the collecting optical system and then using a spacer of appropriate size at the center of the fiber bundle to act as a central obstruction.

Claims

1. An apparatus for enhancing spectroscopic measurements of one or more analytes in a sample, the apparatus comprising:

optics that collect light scattered from a sample illuminated by a source of optical radiation, the sample containing one or more analytes;

a fiber bundle containing a plurality of optical fibers, wherein a first end of the fiber bundle is positioned to receive the scattered light collected by the optics, and the optical fibers are arranged within the first end of the fiber bundle to reduce the strength of light received that is scattered from or around a surface of the sample;

a spectroscopic apparatus positioned to receive light from a second end of the fiber bundle, that divides the received light according to wavelength; and

one or more optical detectors that receive the wavelength-divided light from the spectroscopic apparatus.

2. The apparatus of claim 1, wherein at the first end of the fiber bundle, the optical fibers are arranged in a circular type pattern but largely avoiding a central location of the circular type pattern.

3. The apparatus of claim 2, wherein, at the second end of the fiber bundle, the optical fibers are arranged in a slit type pattern.

4. The apparatus of claim 2, wherein the first end of the fiber bundle is positioned at an image plane of the optics.

5. The apparatus of claim 2, further comprising an optical obscuration located at the central location of the circular type pattern.

6. The apparatus of claim 5, wherein, at the first end of the fiber bundle, the optical fibers are separated by the optical obscuration but, at the second end of the fiber bundle, the optical fibers are closely packed.

7. The apparatus of claim 5, wherein a cross-sectional area of the optical obscuration is less than a collective cross-sectional area of the optical fibers at the first end of the fiber bundle.

8. The apparatus of claim 5, wherein the first end of the fiber bundle is centered on an image of the source of optical radiation.

9. The apparatus of claim 8, wherein, at the surface of the sample, a diameter of the image of the source of optical radiation is less than a diameter of an image of the optical obscuration.

10. The apparatus of claim 1, wherein the sample is of biological origin.

11. The apparatus of claim 10, wherein the sample is human tissue.

12. The apparatus of claim 10, wherein the sample is human skin.

13. The apparatus of claim 1, wherein a first analyte of the analytes is substantially absent from and around a surface of the sample, and the light collected by the optics and received by the fiber bundle includes light scattered by the first analyte.

14. The apparatus of claim 1, further comprising the source of optical radiation that illuminates the sample, wherein a wavelength of the source is between 600 nm and 1300 nm.

15. The apparatus of claim 1, wherein the source of optical radiation comprises a laser.

16. An apparatus for enhancing spectroscopic measurements of one or more analytes in a sample, the apparatus comprising:

optics that collect light scattered from a sample illuminated by a source of optical radiation, the sample containing one or more analytes;

a spatial filter positioned to reduce the strength of light scattered from or around a surface of the sample and collected by the optics;

a spectroscopic apparatus positioned to receive the scattered light collected by the optics, that divides the received light according to wavelength; and

one or more optical detectors that receive the wavelength-divided light from the spectroscopic apparatus.

17. The apparatus of claim 16, wherein the spatial filter is a central obscuration located in an image plane of the optics.

18. The apparatus of claim 17, wherein, at the surface of the sample, a diameter of the image of the source of optical radiation is less than a diameter of an image of the optical obscuration.

19. The apparatus of claim 17, wherein the central obscuration is an annular obscuration.

20. The apparatus of claim 16, wherein the sample is of biological origin.

21. The apparatus of claim 20, wherein the sample is human tissue.

22. The apparatus of claim 20, wherein the sample is human skin.

23. The apparatus of claim 16, wherein a first analyte of the analytes is substantially absent from and around a surface of the sample, and the light collected by the optics includes light scattered by the first analyte.

24. The apparatus of claim 16, further comprising the source of optical radiation, wherein a wavelength of the source is between 600 nm and 1300 nm.