Sampling of time- and frequency-domain signals in Monte Carlo simulations of photon migration

We compare two fundamentally different ways to evaluate the time dependence in Monte Carlo simulations of photon migration: estimating the pulse respo nse in time versus evaluating the transfer function at discrete points in t he frequency domain. We show that these two methods differ in accuracy owin g to quantization and sampling errors, whereas the statistical error is ess entially the same for both methods. From our analysis we also derive altern ative methods to sample the time-domain pulse response with reduced quantiz ation and sampling error. Simulation results are included to illustrate our theoretical analysis. (C) 1999 Optical Society of America.