Does the photon-diffusion coefficient depend on absorption?

We investigate the controversy over the precise form of the photon diffusion coefficient and suggest that it is largely independent of absorption, i.e., D-o = upsilon/3 mu'(s). After presentation of the general theoretical arguments underlying this assertion, Monte Carlo simulations are performed and explicitly reveal that the absorption-independent diffusion coefficient gives better agreement with theory than the traditionally accepted photon diffusion coefficient, D-mu alpha = upsilon/3(mu'(s) + mu(alpha)). The importance of resolving this controversy for the proper characterization of the material optical properties is discussed. (C) 1997 Optical Society of America.