ECE532 Biomedical Optics
Steven L. Jacques, Scott A. Prahl
Oregon Graduate Institute
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Chapter 4

Time-resolved Monte Carlo:


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

survival = exp(-µaL)

µa = 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

c = the speed of light in the medium (c = co/n)
t = time [s]

At any point in time, one can calculate the probability of photon survival by exp(-µaL) = exp(-µact).

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