Investigation of the Optical Diffusion Coefficient in Turbid Media by the Added-Absorber Method

The dependence of the optical diffusion coefficient D on the absorption coefficient μa was investigated. The spatial intensity distribution of light emitted by a low frequency intensity-modulated diode laser was studied in aqueous suspensions of pmma latex beads. The absorption coefficient of the suspensions was gradually increased by adding the dye isosulfan blue (isb) up to a ratio between the absorption and the effective scattering coefficient of the mixture of 3.6. Conventional transmission measurements showed that the absorption coefficient of the mixture increases linearly in the entire concentration range employed. The measurements were evaluated in the framework of photon diffusion theory. The results obtained indicated that for the suspensions investigated the optical diffusion coefficient does depend on absorption.