Abstract: An arithmetic control mechanism of the present optical CT apparatus calculates first light densities in output portions of an object on the basis of a numerical analysis method, when it is assumed that the object is divided into fine segments and all segments have the same value as an absorption coefficient under predetermined conditions equivalent to an actual measurements; and calculates second light densities in the output portions on the basis of the method, when it is assumed that sequentially selected one of the segments has a specific value as an absorption coefficient under the predetermined conditions.

Abstract: Measuring scattering and absorption properties of a scattering medium according to the following: (a) causing pulsed measuring light having a predetermined wavelength to enter the scattering medium; (b) performing time-resolved measurement of the measuring light having diffusively propagated in the scattering medium at light detection positions corresponding to a plurality of combinations, each comprising a light incidence position on the scattering medium in the first step and a light detection position on the scattering medium where the measuring light entered the scattering medium in the first step and a light detection position on the scattering medium where the measuring light is detected, having different incidence-detection distances between the light incidence position and the light detection position; (c) calculating a plurality of mean optical pathlengths of the measuring light corresponding to the plurality of incidence-detection distances, based on results of the time-resolved measurement measured