High-frequency limit of photon density waves in turbid media

We propose an iterative scheme to compute quasi-analytically the laser irradiance transmitted through a turbid media illuminated by high-frequency intensity-modulated light. We compare the spatial distribution of the transmitted signal obtained from iterative calculations with that obtained from random walk simulations and from the traditional diffusion theory. In the regime where the diffusion theory breaks down for a highly modulated source, only the ballistic and quasi-ballistic photons survive. This regime could become accessible for interesting imaging applications as the beam width of the AC signal of the transmitted light decreases with an increasing frequency.