Instrument for measurement of optical parameters of turbid media by using diffuse reflectance of laser with oblique incidence angle

An instrument for simultaneous measurement of absorption and reduced scattering coefficients of optically turbid materials is presented. Determination of the coefficient is based on scattering profile of a laser beam illuminating the sample at oblique incidence angle. The back reflected profile is recorded by imaging the scattered laser spot on material surface, and the coefficients calculated by determining the asymmetry and the slope of the reflectance profile. Several phantoms having different combinations of absorption and scattering coefficients were measured. Results were in good agreement with the reference values with absolute errors from 0.005 to 0.46 mm^-1 and from 0.034 to 0.25 mm^-1 for absorption and reduced scattering coefficients, respectively, and strong linear dependency with the reference values.