Light Reflection and Transmission by Non-Absorbing Turbid Slabs: Simple Approximations

A simple approximation is developed for the total reflectance and transmittance of non-absorbing turbid plane-parallel layers. It is based on the energy conservation law and asymptotic equations for optically thick turbid slabs. The accuracy of the approximation is better than 1.5% at optical thickness larger than unity. This is comparable with the accuracy of many numerical schemes for the solution of the radiative transfer equation.