The diffuse reflection and transmission of light by a plane-parallel suspension of randomly oriented particles, scattering independently, are treated using radiative-transfer theory. Exact allowance is made for external and internal reflection at the plane surfaces of the matrix. General equations are derived in a form suitable for automatic computation. Some comparisons made between theoretical predictions and experimental measurements of the total transmittance of an optically thick diffusing suspension show satisfactory agreement with radiative-transfer theory and also with the Eddington approximation.
S. E. ORCHARD, "Reflection and Transmission of Light by Diffusing Suspensions," J. Opt. Soc. Am. 59, 1584-1597 (1969)