Optical spectroscopy pathlength measurement system
First Claim
1. An optical pathlength measurement system for determining a pathlength of a light source passing through a tissue sample comprising:
- an optical emitter for emitting light of one or more wavelengths;
a first filter for filtering the light emitted from the optical emitter;
a magnetic field generator for optically rotating the light as it passes through a tissue sample;
a second filter for filtering the light after it passes through the tissue sample;
a detector for detecting the light after it passes through the second filter; and
a processor for determining and outputting a pathlength of the light emitted from the optical emitter based on the optical rotation of the light for use in determining a physiological characteristic of the tissue sample.
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Accused Products
Abstract
A physiological monitor utilizes rotation measurements to estimate mean photon pathlengths through tissue. These pathlength estimates, along with corresponding optical spectroscopy measurements allow the noninvasive monitoring of blood constituent concentrations. The technique is particularly applicable to noninvasive blood glucose measurements. The physiological monitor has a polarized light source for illuminating tissue and a magnetic field generator which creates a magnetic field within the tissue during illumination. The magnetic field imparts a rotation in the plane of polarization of the incident light beam as it propagates through the tissue and emerges as a transmitted light beam. A polarimeter is used to measure the rotation of the transmitted light. A signal processor then computes an estimate of the mean pathlength from the polarimeter output. The polarized light source has a multiple wavelength optical emitter and, in conjunction with the polarimeter detector, also functions as a spectrometer. The signal processor combines spectroscopic measurements at various wavelengths with corresponding mean pathlength estimates to compute blood constituent concentrations.
746 Citations
18 Claims
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1. An optical pathlength measurement system for determining a pathlength of a light source passing through a tissue sample comprising:
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an optical emitter for emitting light of one or more wavelengths; a first filter for filtering the light emitted from the optical emitter; a magnetic field generator for optically rotating the light as it passes through a tissue sample; a second filter for filtering the light after it passes through the tissue sample; a detector for detecting the light after it passes through the second filter; and a processor for determining and outputting a pathlength of the light emitted from the optical emitter based on the optical rotation of the light for use in determining a physiological characteristic of the tissue sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of determining an optical pathlength of a light after it passes through a tissue sample comprising:
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irradiating a beam of light; applying a first filter to the light; applying a field configured to optically rotate the light as it passes through a tissue sample; applying a second filter to the light; detecting the rotation of the light; calculating a pathlength based on the rotation of the light. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. An optical pathlength measurement system for determining a pathlength of a light source passing through a tissue sample comprising:
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means for emitting light of one or more wavelengths; means for filtering the light emitted from the multiple wavelength optical emitter; means for optically rotating the light as it passes through a tissue sample; a second means for filtering the light after it passes through the tissue sample; means for detecting the light after it passes through the second polarizer; and means for determining and outputting a pathlength of the light emitted from the multiple wavelength optical emitter based on the optical rotation of the polarized light for use in determining a physiological characteristic of the tissue sample.
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Specification