Method for measuring internal information in a scattering medium and apparatus for the same
First Claim
1. A method for measuring a scattering medium comprising:
- emitting light having a predetermined wavelength;
causing said light to be incident on a scattering medium through a light incident point so that said light has various incident angle components at the light incident point;
detecting the light having said predetermined wavelength, diffused during propagation in said scattering medium at a photodetection point different from the light incident point to obtain an optically detected signal;
processing said optically detected signal to detect a predetermined parameter, said predetermined parameter being primary information relating to a scattering characteristic and an absorption characteristic on a diffusion-propagation path, and being selected from the group consisting of a phase delay of a signal having a predetermined modulated frequency component included in said optically detected signal, a time integral value of time-waveform of said optically detected signal, a delay time of time-waveform of said optically detected signal, a differential coefficient of time-waveform of said optically detected signal and an amplitude of a signal having a predetermined modulated frequency component included in said optically detected signal; and
processing said predetermined parameter based on a relation between a scattering characteristic and an absorption characteristic corresponding to said light having said predetermined wavelength on said diffusion-propagation path, and said predetermined parameter to calculate internal information in said scattering medium, said relation being a solution of a photon diffusion equation obtained by using an assumption that light diffusion of said light starts immediately from the light incident point, said internal information being secondary information and being selected from the group consisting of an absorption coefficient, a transport scattering coefficient and an effective attenuation coefficient.
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Abstract
Light having a predetermined wavelength and various incident angle components to be incident on a surface of a scattering medium to generate an equivalent point light source or a group of equivalent point light sources near or on the surface of the scattering medium, and light diffused during propagation in the scattering medium is detected outside, and considering isotropic light from the equivalent light sources is immediately diffused, the optically detected signal is processed to detect a predetermined parameter which is primary information and this predetermined parameter is processed to measure internal information which is secondary information in the scattering medium with high accuracy.
41 Citations
25 Claims
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1. A method for measuring a scattering medium comprising:
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emitting light having a predetermined wavelength; causing said light to be incident on a scattering medium through a light incident point so that said light has various incident angle components at the light incident point; detecting the light having said predetermined wavelength, diffused during propagation in said scattering medium at a photodetection point different from the light incident point to obtain an optically detected signal; processing said optically detected signal to detect a predetermined parameter, said predetermined parameter being primary information relating to a scattering characteristic and an absorption characteristic on a diffusion-propagation path, and being selected from the group consisting of a phase delay of a signal having a predetermined modulated frequency component included in said optically detected signal, a time integral value of time-waveform of said optically detected signal, a delay time of time-waveform of said optically detected signal, a differential coefficient of time-waveform of said optically detected signal and an amplitude of a signal having a predetermined modulated frequency component included in said optically detected signal; and processing said predetermined parameter based on a relation between a scattering characteristic and an absorption characteristic corresponding to said light having said predetermined wavelength on said diffusion-propagation path, and said predetermined parameter to calculate internal information in said scattering medium, said relation being a solution of a photon diffusion equation obtained by using an assumption that light diffusion of said light starts immediately from the light incident point, said internal information being secondary information and being selected from the group consisting of an absorption coefficient, a transport scattering coefficient and an effective attenuation coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18)
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16. An apparatus for measuring a scattering medium comprising:
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a light source for emitting light having a predetermined wavelength; light-incident means for causing said light to be incident on a scattering medium through a light incident point so that said light has simultaneous multiple angles of incidence various incident angle components at the light incident point; photodetecting means for detecting said light having said predetermined wavelength diffused during propagation in said scattering medium at a photodetecting point different from the light incident point to obtain an optically detected signal; parameter arithmetic processing means for processing said optically detected signal to detect a predetermined parameter, said predetermined parameter being primary information relating to a scattering characteristic and an absorption characteristic on a diffusion-propagation path, and being selected from the group consisting of a phase delay of a signal having a predetermined modulated frequency component included in said optically detected signal, a time integral value of time-waveform of said optically detected signal, a delay time of time-waveform of said optically detected signal, a differential coefficient of time-waveform of said optically detected signal and an amplitude of a signal having a predetermined modulated frequency component included in said optically detected signal; and internal information arithmetic processing means for processing said predetermined parameter, on assumption that said light is diffused immediately after incidence from the light incident point, based on a relation between a scattering characteristic and an absorption characteristic corresponding to said light having said predetermined wavelength on said diffusion-propagation path, and said predetermined parameter to calculate internal information in said scattering medium, said relation being a solution of a photon diffusion equation obtained by using an assumption that light diffusion of said light starts immediately from the light incident point, said internal information being secondary information and being selected from the group consisting of an absorption coefficient, a transport scattering coefficient and an effective attenuation coefficient. - View Dependent Claims (17, 19, 20, 21, 22, 23, 24, 25)
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Specification