Patent ID: 6567165
Filing Date: 2003-05-20
Classification: G01N

Abstract:
A concentration measuring method for an absorption component in a scattering medium, comprising:a light generation step of generating at least two light rays having predetermined wavelengths, the light rays having different transport scattering coefficients for a scattering medium as an object to be measured, and a known ratio of the transport scattering coefficients; a light incidence step of making the light rays incident from a light incident position into the scattering medium; a photodetection step of detecting the light ray which has propagated inside the scattering medium at at least one photodetection position different from the light incident position to acquire at least one photodetection signal; a parameter detection step of detecting, on the basis of the photodetection signal, a light intensity and a mean flight pathlength at the light detection position for each of the at least two light rays having predetermined wavelengths; and an arithmetic processing step of calculating a concentration of an absorption component on the basis of a predetermined relationship between the ratio of the transport scattering coefficients, the light intensity, the mean flight pathlength, and a difference between absorption coefficients per unit concentration of the absorption component for the at least two light rays having predetermined wavelengths, said predetermined relationship being a relationship derived on the basis of a fact that a value obtained by partially differentiating a natural logarithm of the detected light intensity by the absorption coefficient equals the mean flight pathlength without neglecting a difference in mean flight pathlength due to the difference in scattering coefficients.