Intensity Distribution of Waves Transmitted Through a Multiple   Scattering Medium
  The distributions of the angular transmission coefficient and of the total transmission are calculated for multiple scattered waves. The calculation is based on a mapping to the distribution of eigenvalues of the transmission matrix. The distributions depend on the profile of the incoming beam. The distribution function of the angular transmission has a stretched exponential decay. The total-transmission distribution grows log-normally whereas it decays exponentially. 
Th. M. Nieuwenhuizen and M. C. W. van Rossum