| ECE532 Biomedical Optics
© 1998
Steven L. Jacques, Scott A. Prahl
Oregon Graduate Institute |

# Time-resolved Monte Carlo

## Introduction

We are already familiar with the simple Beer's Law description of photon survival in an absorbing medium:

survival = exp(-µ_{a}L)
- µ
_{a} - absorption coefficient [cm
^{-1}]

- L
- pathlength of photon travel [cm]

In a scattering medium, the photon's path is not a straight line, but Beer's law still holds. Regardless of how tortuous the path, the pathlength is given by:

- L=ct
- Pathlength
- c
- the speed of light in the medium (c = c
_{o}/n)

- t
- time [s]

At any point in time, one can calculate the probability of photon survival by exp(-µ_{a}L) = exp(-µ_{a}ct).

Next •
Monte Carlo