Reflection and transmission coefficients for diffuse photon density waves

Diffuse photon density waves are proposed for use in characterizing diffuse media, similar to the use of electro-magnetic waves to characterize reflection from materials. To this end basic expressions for the reflection and transmission coefficients at interfaces are put forward. Effects such as the existence of modes analogous with Brewster modes are shown. Also, we illustrate through numerical simulations how the diffusion optical parameters are estimated both with and without noise in the data.