Phase modulation spectrophotometric apparatus
AssigneeNon-Invasive Technology, Inc.
InventorBritton Chance
Life of this patent
Estimating the term…
Abstract
A pathlength corrected spectrophotometer for tissue examination includes an oscillator for generating a carrier waveform of a selected frequency, an LED light source for generating light of a selected wavelength that is intensity modulated at the selected frequency introduced to a subject, and a photodiode detector for detecting light that has migrated in the tissue of the subject. The spectrophotometer also includes a phase detector for measuring a phase shift between the introduced and detected light, a magnitude detector for determination of light attenuation in the examined tissue, and a processor adapted to calculate the photon migration pathlength and determine a physiological property of the examined tissue based on the pathlength and on the attenuation data.
Claims36
A phase modulation spectroscopic apparatus comprising:
- an optical input port coupled to a light source and an optical detection port coupled to a detector, said input and detection ports being spaced several centimeters apart and arranged for spectroscopic examination of biological tissue;
- a modulator constructed to generate a modulation waveform with a first modulation frequency having a time characteristic compatible with the time delay of photon migration from said optical input port to said optical detection port in the biological tissue;
- said light source coupled to said modulator constructed to provide radiation of a first wavelength, said radiation being modulated at said modulation waveform and introduced into the tissue from said input port;
- said optical detector arranged to detect radiation of said first wavelength having photons that have migrated over migration paths in the examined tissue from said input port to said detection port;
- and
- a phase detector arranged to receive from said optical detector a detected waveform corresponding to said detected photons of said first wavelength and further arranged to compare said detected waveform with said modulation waveform and to determine therefrom a phase shift between said introduced and detected radiation at said first wavelength, said phase shift being indicative of scattering and absorptive properties of the examined tissue.
A spectroscopic apparatus for examination of biological tissue with one or more constituents having specific concentrations and having a quantifiable parameter associated with a particular wavelength of electromagnetic radiation, said apparatus comprising:
- a first light source constructed to introduce first electromagnetic radiation into the tissue at an optical input port;
- a first optical detector arranged to detect said first electromagnetic radiation having photons that have migrated over migration paths in the examined tissue from said input port to a detection port, said first detector providing a detection signal corresponding to the intensity of said detected first radiation;
- a circuitry connected to receive said detection signal from said first detector and arranged to determine intensity of radiation absorbed due to at least one of said constituents;
- and
- an optical system including a second light source constructed to introduce second electromagnetic radiation into the tissue at said optical input port, and a second detector arranged to detect said second electromagnetic radiation having photons that have migrated over migration paths in the examined tissue from said input port to said detection port, said optical system being arranged to determine an optical pathlength of photon migration in the examined tissue between said optical input and detection ports to evaluate a change in concentration of at least one constituent of the tissue.
Dependencies are inferred from the claim text.