Abstract

Monte Carlo method is a statistical method that is built on random sampling of variables from well-defined probability distributions. It has been employed rigorously to study the photon transport in biologically turbid media. This thesis employs a well-established simulation program called "MCML" to study photon transport in biologically turbid media. In the present work, we use Monte Carlo method for modeling finite diameter optical beams, which are in general approximated by uniform or Gaussian intensity distributions. In order to model focused Gaussian beams with Monte Carlo simulation, the "MCML" program was modified based on a probability distribution found in the literature. However, errors were encountered in the calculated physical quantities by Monte Carlo simulation. This error formed a strong motivation to search for and analyze its source. Using simulation, we prove that the probability density function used in the literature is a source of error in the calculations of the physical quantities evaluated by Monte Carlo simulation. We propose another probability density function that is shown to provide a dramatic improvement compared with the other function.