Patent ID: 6643020
Filing Date: 2003-11-04
Classification: G01N

Abstract:
An optical analysis method of determining a physical quantity of a medium from an intensity of light transmitted through or reflected by the medium, the medium being an absorbent and scattering medium containing a plurality of parts having different optical characteristics, characterized by comprising:the first step of making light having a known intensity incident on the medium; the second step of measuring the intensity of the light that emerges from the medium; the third step of storing light intensity numerical values; the fourth step of deriving a coefficient necessary for arithmetic operation by erasing or avoiding influence of inhomogeneous light scattering by arithmetic operation for a combination of the numerical values; the fifth step of storing the obtained coefficient; and the sixth step of performing linear algebraic operation for optimization in a wavelength range using the light intensity measurement values at a plurality of wavelengths, wherein the function used for the arithmetic operation is defined as simultaneous differential equations that describe light amount re-distribution by light scattering between the parts, i.e., a basic system that expresses light re-distribution given by dx/dt=âˆ’ax+by â€ƒdy/dt=cxâˆ’dy whereassuming that the medium contains two, first and second parts, x is a light intensity in the first part, y is a light intensity in the second part, a is a loss coefficient by absorption and scattering in the first part, b is a coefficient of a component of scattered light in the second part, which mixes into the first part, c is a coefficient of a component of scattered light in the first part, which mixes into the second part, d is a loss coefficient by absorption and scattering in the second part, and t is a penetration depth of the light into the inhomogeneous medium, and as a linear sum of exponential functions for t, which uses e as a base and is given by I=x+y=12&it;(&ee;-Î±&it;â€ƒ&it;t+&ee;-Î²&it;â€ƒ&it;t)which represents a light intensity I standardized as a sum of general solutions x and y corresponding to the basic system, thereby derivatively calculating the physical quantity from the light amount measurement values on the basis of a relationship between the coefficients (a, b, c, d) and unknowns (&agr;, &bgr;).