F. Martelli et al., Properties of the light emerging from a diffusive medium: angular dependence and flux at the external boundary, PHYS MED BI, 44(5), 1999, pp. 1257-1275
By using the diffusion approximation of the radiative transfer equation and
the partial-current boundary condition, an analytical expression for the a
ngular dependence of the specific intensity emerging from a diffusive mediu
m has been obtained. The analytical expression for the angular distribution
has been validated by comparisons with the results of Monte Carlo simulati
ons. By using the diffusion equation and the extrapolated boundary conditio
n, an heuristic analytical expression for the diffuse time-resolved reflect
ance has also been obtained by assuming that the photon flux is simply prop
ortional to the fluence rate. For the case of the semi-infinite medium, com
parisons with Monte Carlo results are presented and time-resolved reflectan
ce data are fitted with the simple fluence rate formula. The results obtain
ed show that the simple expression correctly describes the time-resolved re
flectance giving an error in the retrieved optical parameters smaller than
that of other commonly used expressions.