# Photon diffusion coefficient in an absorbing medium

### R. Aronson and N. Corngold (1999)

#### Summary

A number of investigators have recently claimed, based on both analysis from transport theory
and transport-theory-based Monte Carlo calculations, that the diffusion coefficient for photon
migration should be taken to be independent of absorption. We show that these analyses are flawed
and that the correct way of extracting diffusion theory from transport theory gives an
absorption-dependent diffusion coefficient. Experiments by two different sets of investigators
give conflicting results concerning whether the diffusion coefficient depends on absorption. The
discrepancy between theory and the earlier set of experiments poses an interesting challenge.