Stability of the Henyey—Greenstein phase function and fast path integration under conditions of multiple light scattering

It is shown that the stability of the Henyey–Greenstein phase function allows the calculation rate of light propagation through strongly scattering objects to be drastically increased by using the same a priori information on interaction processes as in the initial formulation of the problem. The increase in the calculation rate is accompanied by a gradual impairment of simulation accuracy from the accuracy of the Monte-Carlo method to that of the diffusion approximation. By using a standard assumption about the statistical independence of the photon mean free path and photon scattering angle, an exact analytic expression relating the effective number of scattering events with the optical path is obtained.