Rapid non-invasive optical analysis using broad bandpass spectral processing
First Claim
1. An apparatus for determining the concentration of a constituent of interest in a sample which has transmittance, emittance, or reflectance in a selected region of the spectrum comprising:
- illumination means which generates a plurality of beams of illuminating radiation in a selected region of the spectrum;
coding means for placing an identifiable, distinct code on each of said plurality of beams of radiation;
means for individually limiting the wavelength of each of said plurality of beams such that each beam is limited in wavelength to a distinct portion of said selected region of said spectrum, whereby at least one of said beams covers a broadband spectral region;
transmission means for transmitting said coded beams to illuminate said sample;
detection means for detecting the intensity of radiation transmitted, emitted, or reflected by said sample, said detection means including at least one broad band detector and decoding means for identifying the code on each of said coded beams, said detection means generating output signals which are functions of the information carried by each coded beam; and
analysis means for converting said output signals into a measure of said concentration of said constituent of interest in said sample;
wherein said analysis means generates a response which is an analog of a location in an n-dimensional colorimetric space, where n is equal to, or less than, the number of beams used to illuminate said sample.
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Abstract
The present invention provides a generally applicable apparatus and method for achieving measurements of a constituent in a sample. This is achieved by employing a detection means having a plurality of detectors responsive to radiation in a selected region of the spectrum, e.g., the infrared. In most embodiments, at least two of the detectors provide broad wavelength bandpass. If narrow bandpass sources or detectors are used, the information generated is processed in a manner similar to broadband information. The broad bandpass response of the detectors can be contrasted with the approach of classical spectrophotometry, in which the spectral response of the detectors is designed to be as narrow as feasible, and substantially narrower than the spectral features of the constituent or constituents of interest. The data is processed such that the contributions of known background constituents and scattering is eliminated prior to further processing, thereby yielding a better result in high background situations. The use of intensity processing rather than absorbance processing also allows the method and apparatus to be used in a variety of non-ideal situations.
63 Citations
65 Claims
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1. An apparatus for determining the concentration of a constituent of interest in a sample which has transmittance, emittance, or reflectance in a selected region of the spectrum comprising:
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illumination means which generates a plurality of beams of illuminating radiation in a selected region of the spectrum; coding means for placing an identifiable, distinct code on each of said plurality of beams of radiation; means for individually limiting the wavelength of each of said plurality of beams such that each beam is limited in wavelength to a distinct portion of said selected region of said spectrum, whereby at least one of said beams covers a broadband spectral region; transmission means for transmitting said coded beams to illuminate said sample; detection means for detecting the intensity of radiation transmitted, emitted, or reflected by said sample, said detection means including at least one broad band detector and decoding means for identifying the code on each of said coded beams, said detection means generating output signals which are functions of the information carried by each coded beam; and analysis means for converting said output signals into a measure of said concentration of said constituent of interest in said sample; wherein said analysis means generates a response which is an analog of a location in an n-dimensional colorimetric space, where n is equal to, or less than, the number of beams used to illuminate said sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method for determining the concentration of a constituent of interest in a sample which has transmittance, emittance, or reflectance in a selected region of the spectrum comprising:
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coding each of a plurality of beams of illuminating radiation by placing an identifiable, distinct code thereon; individually optically filtering each of said plurality of beams such that each beam is limited to a distinct portion of said selected region of said spectrum; transmitting said coded beams to illuminate said sample; detecting the intensity of radiation transmitted, emitted, or reflected by said sample; decoding the code on each of said coded beams to generate an output signal which is a function of the information carried by each coded beam; generating a processing input signal which is responsive to selected aspects of the background of the detection system and the sample, and said constituent of interest utilizing the output signal generated from a coded beam from a broadband source, and analyzing said output signals and said processing input signal with an analysis means to generate a measure of said concentration of said constituent of interest in said sample; wherein said analysis means generates a response which is an analog of a location in an n-dimensional colorimetric space, where n is equal to, or less than, the number of beams used to illuminate said sample. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A method for determining the concentration of a constituent of interest in a sample which has transmittance, emittance, or reflectance in a selected region of the spectrum comprising:
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coding each of a plurality of beams of illuminating radiation by placing an identifiable, distinct code thereon; individually optically filtering each of said plurality of beams such that each beam is limited to a distinct portion of said selected region of said spectrum; transmitting said coded beams to illuminate said sample; detecting the intensity of radiation transmitted, emitted, or reflected by said sample; decoding the code on each of said coded beams to generate an output signal which is a function of the information carried by each coded beam; generating a processing input signal which is responsive to selected aspects of the background of the detection system and the sample, and said constituent of interest utilizing the output signal generated by combining the output signals generated from coded beams from some of said detectors to simulate broadband detection, and analyzing said output signals and said processing input signal with an analysis means to generate a measure of said concentration of said constituent of interest in said sample; wherein said analysis means generates a response which is an analog of a location in an n-dimensional colorimetric space, where n is equal to, or less than, the number of beams used to illuminate said sample.
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Specification