The transition from the ballistic to the diffusive regime in a turbid   medium
  By varying the absorption coefficient and width of an intralipid- India ink solution in a quasi one-dimensional experiment, the transition between the ballistic and the diffusive regimes is investigated. The medium's attenuation coefficient changes abruptly between two different values within a single mean-free-path. This problem is analyzed both experimentally and theoretically, and it is demonstrated that the transition location depends on the scattering coefficient as well as on the measuring solid angle. 
Andre Yaroshevsky, Ziv Glasser, Er'el Granot and Shmuel Sternklar
physics.optics cond-mat.dis-nn