Pathlength corrected oximeter and the like
First Claim
1. A spectrophotometer for biological tissue examination, comprising:
- a support structure adapted to be mounted on a subject includingan optical input port located at a first location to introduce light to biological tissue of the subject;
an optical detection port located at a second location on said support structure spaced apart from said input port; and
a barrier constructed and positioned to absorb photons directly propagating from said input port to said detection port;
an oscillator, including oscillator electronics, that generates a carrier waveform of a selected frequency comparable to an average migration time of photons scattered in tissue on paths from said optical input port to said optical detection port, said frequency being above 10 MHz;
a light source mounted on said support structure and connected to and receiving said carrier waveform from said oscillator, said light source generates light of a selected wavelength that is intensity modulated at said frequency and is introduced to the tissue of the subject at said input port;
a photodiode detector mounted on said support structure and connected to said detection port, said photodiode detector detects scattered light of said wavelength that has migrated in examined tissue of the subject between said input and detection ports;
a phase detector, including phase detector electronics, connected to receive signals from said oscillator and said diode detector, said phase detector measures a phase shift between said introduced light and said detected light that has migrated in the examined tissue over photon migration paths from said input port to said detection port; and
a processor connected to receive said phase shift from said phase detector, said processor determines, based on said measured phase shift, a physiological property of the examined tissue dependent on tissue scattering and absorptive properties.
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Accused Products
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.
368 Citations
30 Claims
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1. A spectrophotometer for biological tissue examination, comprising:
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a support structure adapted to be mounted on a subject including an optical input port located at a first location to introduce light to biological tissue of the subject; an optical detection port located at a second location on said support structure spaced apart from said input port; and a barrier constructed and positioned to absorb photons directly propagating from said input port to said detection port; an oscillator, including oscillator electronics, that generates a carrier waveform of a selected frequency comparable to an average migration time of photons scattered in tissue on paths from said optical input port to said optical detection port, said frequency being above 10 MHz; a light source mounted on said support structure and connected to and receiving said carrier waveform from said oscillator, said light source generates light of a selected wavelength that is intensity modulated at said frequency and is introduced to the tissue of the subject at said input port; a photodiode detector mounted on said support structure and connected to said detection port, said photodiode detector detects scattered light of said wavelength that has migrated in examined tissue of the subject between said input and detection ports; a phase detector, including phase detector electronics, connected to receive signals from said oscillator and said diode detector, said phase detector measures a phase shift between said introduced light and said detected light that has migrated in the examined tissue over photon migration paths from said input port to said detection port; and a processor connected to receive said phase shift from said phase detector, said processor determines, based on said measured phase shift, a physiological property of the examined tissue dependent on tissue scattering and absorptive properties. - View Dependent Claims (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)
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2. A spectrophotometer for biological tissue examination, comprising:
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a support structure adapted to be mounted on a subject including an optical input port located at a first location to introduce light to biological tissue of the subject; an optical detection port located at a second location on said support structure spaced apart from said input port; and a barrier constructed and positioned to absorb photons directly propagating from said input port to said detection port; an oscillator, including oscillator electronics, that generates a carrier waveform of a selected frequency comparable to an average migration time of photons scattered in tissue on paths from said optical input port to said optical detection port, said frequency being above 10 MHz; a light source mounted on said support structure and connected to and receiving said carrier waveform from said oscillator, said light source generates light of a selected wavelength that is intensity modulated at said frequency and is introduced to the tissue of the subject at said input port; a photodiode detector, mounted on said support structure and connected to said detection port, said photodiode detector detects scattered light of said wavelength that has migrated in examined tissue of the subject between said input and detection ports and produces a detector signal; a phase splitter, including a phase splitter circuit, that receives said carrier waveform and produces, first and second reference phase signals of predefined substantially different phases; first and second double balanced mixers, including corresponding mixer circuits, that receive and correlate said reference phase signals and said detector signals to produce therefrom a real output signal and an imaginary output signal, respectively; a processor connected to receive from said mixers said real output signal and said imaginary output signal, said processor determines from real output signal and an imaginary output signal a phase shift between said introduced light and said detected light; and said processor further determines, based on said phase shift, a physiological property of the examined tissue dependant on tissue scattering or absorptive properties. - View Dependent Claims (3)
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4. A spectrophotometer for biological tissue examination, comprising:
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a support structure adapted to be mounted on a subject including an optical input port located at a first location to introduce light to biological tissue of the subject; an optical detection port located at a second location on said support structure spaced apart from said input port; and a barrier constructed and positioned to absorb photons directly propagating from said input port to said detection port; a first oscillator, including oscillator electronics, that generates a carrier waveform of a first selected frequency comparable to an average migration time of photons scattered in tissue on paths from said optical input port to said optical detection port, said frequency being above 10 MHz; a light source mounted on said support structure and connected to and receiving said carrier waveform from said oscillator, said light source generates light of a selected wavelength that is intensity modulated at said first frequency and is introduced to the tissue of the subject at said input port; a photodiode detector mounted on said support structure and connected to said detection port, said photodiode detector detects light of said wavelength that has migrated in examined tissue of the subject between said input and detection ports and produces a detection signal at said first frequency corresponding to said detected light; a second oscillator, including oscillator electronics, that generates a carrier waveform of a second frequency; a reference mixer, including mixer electronics, connected to said first and second oscillators, said reference mixer generates a reference signal of a frequency approximately equal to the difference between said first and second frequencies; a mixer, including mixer electronics, connected to receive signals from said second oscillator and said detection signal, said mixer converts said detection signal to a converted detection signal at said difference frequency; a phase detector, including phase detector electronics, connected to receive reference signals from said reference mixer and said converted detection signal from said mixer, said phase detector measures a phase shift between said introduced light and said detected light that has migrated in the examined tissue over photon migration paths from said input port to said detection port; and a processor connected to receive phase shift signal from said phase detector, said processor determines, based on said measured phase shift, a physiological property of the examined tissue dependent on tissue scattering or absorptive properties.
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Specification