Non-spectrophotometric measurement of analyte concentrations and optical properties of objects

• US 5,818,044 A
• Filed: 02/02/1995
• Issued: 10/06/1998
• Est. Priority Date: 07/15/1992
• Status: Expired due to Fees

• Current Assignee: Optix LP
• Original Assignee: Optix LP
• Inventors: Block, Myron J., Sodickson, Lester
• Primary Examiner(s): Willis, Davis L.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US08/383,293
• Time in Patent Office: 1,342 Days
• Field of Search: 250/339.09, 250/341.1, 250/341.8, 250/343, 356/405
• US Class Current: 250/339.06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: G01N 2021/3137 with selection of wavelengths after the sample
• 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 21/359 using near infrared light
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

Improvement methods and apparatus for determination of optical properties of objects have been developed. The apparatus and methods of the invention provide an analog of color perception of human vision, preferably in the near infrared region, replacing spectrophotometers and narrow band sources used in other non-invasive near infrared detection methods. A plurality of detector units are used, each covering a broad and overlapping region of the detected spectrum, paralleling color perception and colorimetry. The improvements are primarily concerned with improving the signal-to-background (or noise) ratio such that the data stream is improved. These improvements use congruent sampling, comparison of different data streams from different sample portions or filter sets, using an interrogation system with sufficient speed to allow testing of arterial blood, and using a filter with a spectral structure. In some circumstances, a neural net is used for analysis, allowing the system to learn. A novel method for background discrimination is also described.

Claims

1. In an apparatus for determining the optical properties of an object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said object;

detection means having three or more detectors adapted to generate an output, each of said detectors having a spectral response in a portion of said spectrum of illuminating radiation emitted by said radiation source, each of said detectors having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of at least one other of said detectors; and

analysis means for analyzing said outputs from the detectors to generate a signal indicative of the optical properties of said object;

the improvement comprising;

said apparatus being constructed such that each of said detectors is located such that it congruently samples the radiation from said object.

2. The apparatus of claim 1 wherein said illuminating radiation comprises infrared radiation in the 700-2500 nm range.

3. The apparatus of claim 1 wherein said analysis means generates an output which is an analog of a location in a colorimetric n-dimensional space, n being equal to, or less than, the number of detectors in said detection means.

4. The apparatus of claim 1 wherein said detector means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors.

5. The apparatus of claim 1 wherein each of said detectors comprises a filter which transmits or reflects a portion of said spectrum of illuminating radiation, each of said filters having a separate peak transmittance or absorbance response different from the peak transmittance or reflectance responses of the other filters of said detection means and at least a partial overlap in transmittance or reflectance response with at least one other of said filters.

6. The apparatus of claim 1 wherein said analysis means comprises a neural network.

7. The apparatus of claim 1 wherein at least one of said three or more detectors comprise a silicon photocell.

8. The apparatus of claim 1 comprising beam splitting means to allow said three or more detectors to be arranged to achieve congruent sampling.

9. The apparatus of claim 1 comprising a fiber optic cable bundle containing a plurality of optical fibers to allow said three or more detectors to be arranged to achieve congruent sampling.

10. In an apparatus for determining the optical properties of an object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said sample;

detection means having three or more detectors adapted to generate an output, each of said detectors having a spectral response in a portion of said spectrum of illuminating radiation emitted by said radiation source, each of said detectors having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of at least one other of said detectors; and

analysis means for analyzing the outputs from said detectors to generate a data signal component indicative of the optical properties of said object;

the improvement comprising;

having at least two detection means, a first detection means generating a first data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component, and a second detection means generating a second data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component; and

said analysis means comprising means adapted for comparing said first data stream with said second data stream in order to generate an information signal indicative of the optical properties of said object while rendering the interfering features of the background from said first data stream and said second data stream to be less distinct than the background is in either data stream individually.

11. The apparatus of claim 10 wherein each of said detectors comprises a filter which transmits or reflects a portion of said spectrum of illuminating radiation, each of said filters having a peak transmittance or reflectance response different from the peak transmittance or reflectance responses of the other filters of said detection means and at least to a partial overlap in transmittance or absorbance response with at least one other filter, said first detection means having a first set of filters and said second detection means having a second set of filters, and said first and second sets of filters having differing transmittance or reflectance responses.

12. The apparatus of claim 10 wherein said illuminating radiation comprises infrared radiation in the 700-2500 nm range.

13. The apparatus of claim 10 wherein said analysis means generates an analog of a location in a colorimetric n-dimensional space from said first data stream, where n is equal to or less than, the number of detectors in each of said first detection means;

an analog of a location in a colorimetric m-dimensional space from said second data stream, where m is equal to or less than, the number of detectors in said second detection means; and

compares said locations to generate said data signal component indicative of the optical properties of said object.

14. The apparatus of claim 10 wherein at least one of said detection means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors in said detection means.

15. The apparatus of claim 10 wherein said analysis means comprises a neural network.

16. The apparatus of claim 10 wherein at least one of said three or more detectors comprises a silicon photocell.

17. In an apparatus for determining the optical properties of an object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said object;

detection means having three or more detectors adapted to generate an output, each of said detectors having a spectral response to a portion of said spectrum of illuminating radiation emitted by said radiation source, each of said detector having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of a least one other of said detectors; and

analysis means for analyzing the outputs from said detectors to generate a data signal component indicative of the optical properties of said object;

the improvement comprising;

having at least two detection means, a first detection means adapted to receive radiation transmitted or reflected from a first object portion, said first detection means generating a first data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component, and a second detection means adapted to receive radiation transmitted or reflected from a first object portion, said second detector means generating a second data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component; and

said analysis means comprising means adapted for comparing said first data stream with said second data stream in order to generate an information signal indicative of the optical properties of said object while rendering the interfering features of the background from said first data stream and said second data stream to be less distinct than the background is in either data stream individually.

18. The apparatus of claim 17 wherein each of said detectors has a filter with a peak spectral response different from the peak spectral responses of the other filters of said detection means and at least a partial overlap in spectral response with at least one other filter, said first detection means having a first set of filters and said second detection means having a second set of filters, and said first and second sets of filters having differing spectral transmittance or reflectance responses.

19. The apparatus of claim 17 wherein said illuminating radiation comprises infrared radiation in the 700-2500 nm range.

20. The apparatus of claim 17 wherein said analysis means generates an analog of a location in a colorimetric n-dimensional space from said first data stream, where n is equal to or less than, the number of detectors in each of said first detection means;

an analog of a location in a colorimetric m-dimensional space from said second data stream, where m is equal to or less than, the number of detectors in said second detection means; and

compares said locations to generate said data signal component indicative of the optical properties of said object.

21. The apparatus of claim 17 wherein at least one of said detection means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors in said detection means.

22. The apparatus of claim 17 wherein said analysis means comprises a neural network.

23. The apparatus of claim 17 wherein at least one of said three or more detectors comprises a silicon photocell.

24. In an apparatus for determining the optical properties of an object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said object;

detection means having three or more detectors adapted to generate an output, each of said detectors having a filter which transmits or reflects a portion of the spectrum of illuminating radiation emitted by said radiation source, each of said filters having a separate peak transmittance or reflection response and at least a partial overlap in transmittance or reflectance characteristics with at least one other of said filters; and

analysis means for analyzing the outputs from the detectors to generate a signal indicative of the optical properties of said object;

the improvement comprising;

having at least one of said detectors in said detection means has a filter associated therewith which is selected from the group consisting of comb filters having spectral structure such that it has absorbance bands in the portion of the spectrum over which it transmits or reflects radiation, and filters which have only a single narrow transmittance or reflectance range.

25. The apparatus of claim 24 wherein said illuminating radiation comprises infrared radiation in the 700-2500 nm range.

26. The apparatus of claim 24 wherein said analysis means generates an output which is an analog of a location in a colorimetric n-dimensional space, n being equal to, or less than, the number of detectors in said detection means.

27. The apparatus of claim 24 wherein said detector means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said plurality of detectors.

28. The apparatus of claim 24 wherein said analysis means comprises a neural network.

29. The apparatus of claim 24 wherein at least one of said three or more detectors comprises a silicon photocell.

30. In an apparatus for determining the optical properties of a fluorescent object having:

a radiation source generating a spectrum of illuminating radiation for illuminating at least a portion of said object;

detection means having three or more detectors adapted to generate an output, each of said detectors having a spectral response in a portion of the spectrum of fluorescent radiation emitted by said object upon illumination, each of said detectors having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of at least one other of said detectors; and

analysis means for analyzing said outputs from the detectors to generate a signal indicative of the optical properties of said object;

the improvement comprising;

said apparatus being constructed such that each of said detectors is located such that it congruently samples the radiation from said object.

31. The apparatus of claim 30 wherein said fluorescent radiation comprises infrared radiation in the 700-2500 nm range.

32. The apparatus of claim 30 wherein said analysis means generates an output which is an analog of a location in a colorimetric n-dimensional space, n being equal to, or less than, the number of detectors in said detection means.

33. The apparatus of claim 30 wherein said detector means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors.

34. The apparatus of claim 30 wherein each of said detectors comprises a filter which transmits or reflects a portion of said spectrum of fluorescent radiation, each of said filters having a separate peak transmittance or absorbance response different from the peak transmittance or reflectance responses of the other filters of said detection means and at least a partial overlap in transmittance or reflectance response with at least one other of said filters.

35. The apparatus of claim 30 wherein said analysis means comprises a neural network.

36. The apparatus of claim 30 wherein at least one of said three or more detectors comprise a silicon photocell.

37. The apparatus of claim 30 comprising beam splitting means to allow said three or more detectors to be arranged to achieve congruent sampling.

38. The apparatus of claim 30 comprising a fiber optic cable bundles containing a plurality of optical fibers to allow said three or more detectors to be arranged to achieve congruent sampling.

39. In an apparatus for determining the optical properties of a fluorescent object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said sample;

detection means having three or more detectors adapted to generate an output, each of said detectors having a spectral response in a portion of the spectrum of fluorescent radiation emitted by said object upon illumination, each of said detectors having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of at least one other of said detectors; and

analysis means for analyzing the outputs from said detectors to generate a data signal component indicative of the optical properties of said object;

the improvement comprising;

having at least two detection means, a first detection means generating a first data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component, and a second detection means generating a second data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component; and

said analysis means comprising means adapted for comparing said first data stream with said second data stream in order to generate an information signal indicative of the optical properties of said object while rendering the interfering features of the background from said first data stream and said second data stream to be less distinct than the background is in either data stream individually.

40. The apparatus of claim 39 wherein each of said detectors comprises a filter which transmits or reflects a portion of said spectrum of fluorescent radiation, each of said filters having a peak transmittance or reflectance response different from the peak transmittance or reflectance responses of the other filters of said detection means and at least to a partial overlap in transmittance or absorbance response with at least one other filter, said first detection means having a first set of filters and said second detection means having a second set of filters, and said first and second sets of filters having differing transmittance or reflectance responses.

41. The apparatus of claim 39 wherein said fluorescent radiation comprises infrared radiation in the 700-2500 nm range.

42. The apparatus of claim 39 wherein said analysis means generates an analog of a location in a colorimetric n-dimensional space from said first data stream, where n is equal to or less than, the number of detectors in each of said first detection means;

an analog of a location in a colorimetric m-dimensional space from said second data stream, where m is equal to or less than, the number of detectors in said second detection means; and

compares said locations to generate said data signal component indicative of the optical properties of said object.

43. The apparatus of claim 39 wherein at least one of said detection means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors in said detection means.

44. The apparatus of claim 39 wherein said analysis means comprises a neural network.

45. The apparatus of claim 39 wherein at least one of said three or more detectors comprises a silicon photocell.

46. In an apparatus for determining the optical properties of a fluorescent object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said object;

detection means having two or more detectors adapted to generate an output, each of said detectors having a spectral response to a portion of the spectrum of fluorescent radiation emitted by said object upon illumination, each of said detector having a separate peak spectral response and at least a partial overlap in spectral response characteristics with that of a least one other of said detectors; and

analysis means for analyzing the outputs from said detectors to generate a data signal component indicative of the optical properties of said object;

the improvement comprising;

having at least two detection means, a first detection means adapted to receive radiation transmitted or reflected from a first object portion, said first detection means generating a first data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component, and a second detection means adapted to receive radiation transmitted or reflected from a first object portion, said second detector means generating a second data stream formed of a composite of a data signal component indicative of said optical properties of said object and a background component; and

said analysis means comprising means adapted for comparing said first data stream with said second data stream in order to generate an information signal indicative of the optical properties of said object while rendering the interfering features of the background from said first data stream and said second data stream to be less distinct than the background is in either data stream individually.

47. The apparatus of claim 46 wherein each of said detectors has a filter with a peak spectral response different from the peak spectral responses of the other filters of said detection means and at least a partial overlap in spectral response with at least one other filter, said first detection means having a first set of filters and said second detection means having a second set of filters, and said first and second sets of filters having differing spectral transmittance or reflectance responses.

48. The apparatus of claim 46 wherein said fluorescent radiation comprises infrared radiation in the 700-2500 nm range.

49. The apparatus of claim 46 wherein said analysis means generates an analog of a location in a colorimetric n-dimensional space from said first data stream, where n is equal to or less than, the number of detectors in each of said first detection means;

an analog of a location in a colorimetric m-dimensional space from said second data stream, where m is equal to or less than, the number of detectors in said second detection means; and

compares said locations to generate said data signal component indicative of the optical properties of said object.

50. The apparatus of claim 46 wherein at least one of said detection means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors in said detection means.

51. The apparatus of claim 46 wherein said analysis means comprises a neural network.

52. The apparatus of claim 46 wherein at least one of said three or more detectors comprises a silicon photocell.

53. In an apparatus for determining the optical properties of a fluorescent object having:

a radiation source generating a spectrum of illuminating radiation for illuminating a portion of said object;

detection means having three or more detectors adapted to generate an output, each of said detectors having a filter which transmits or reflects a portion of the spectrum of fluorescent radiation emitted by said object, each of said filters having a separate peak transmittance or reflection response and at least a partial overlap in transmittance or reflectance characteristics with at least one other of said filters; and

analysis means for analyzing the outputs from the detectors to generate a signal indicative of the optical properties of said object;

the improvement comprising;

having at least one of said detectors in said detection means has a filter associated therewith which is selected from the group consisting of comb filters having spectral structure such that it has absorbance bands in the portion of the spectrum over which it transmits or reflects radiation, and filters which have only a single narrow transmittance or reflectance range.

54. The apparatus of claim 53 wherein said fluorescent radiation comprises infrared radiation in the 700-2500 nm range.

55. The apparatus of claim 53 wherein said analysis means generates an output which is an analog of a location in a colorimetric n-dimensional space, n being equal to, or less than, the number of detectors in said detection means.

56. The apparatus of claim 53 wherein said detector means further comprises a black/white luminosity detector which is responsive to and overlaps said spectral response of all of said three or more detectors.

57. The apparatus of claim 53 wherein said analysis means comprises a neural network.

58. The apparatus of claim 53 wherein at least one of said three or more detectors comprises a silicon photocell.