Efficient analysis of temporal broadening of a pulsed focused Gaussian beam in scattering media

We show that the temporal broadening of a pulsed, tightly focused TEM,, beam propagating in a scattering medium can be accurately modeled as a convolution between the initial pulse profile and an effective impulse response that is given by the propagation behavior of an infinitely thin pulse in the said medium. The impulse response is obtained with a Monte Carlo (MC) analysis of the propagating photons in the impulse. Our algorithm is 2 orders of magnitude less complex than the full MC solution of the pulse propagation problem. The accuracies, however, are comparable even for scattering path lengths that are 20 times the mean free path. (C) 1999 Optical Society of America.