Time-dependent transport through scattering media: from radiative transfer to diffusion

We study the propagation of light pulses through scattering media using the time-dependent radiative transfer equation. A standard discrete-ordinate method is used to solve this equation in the space-frequency domain. We present calculations of diffuse transmission through scattering slabs, in the presence of absorption and anisotropic scattering. We show that the diffusive regime is attained at long times only for thick slabs. Comparisons with diffusion theory show that the proper choice of the diffusion constant is an important issue for time-dependent transport.