The adding-doubling method is used to calculate reflection and transmission. Since the adding-doubling method is an accurate solution of the radiative transport equation for all albedos, all optical depths, and all phase functions this method can be applied to any medium for which the radiative transport equation is valid. However, a number of restrictions apply. In particular the following assumptions are made distribution of light is independent of time, samples have homogeneous optical properties, tissue geometry is an infinite plane-parallel slab of finite thickness, tissue has a uniform index of refraction, boundaries are smooth, internal reflection is governed by Fresnel's law, and polarization of light may be ignored.
Inverse adding-doubling has a number of advantages and a number of disadvantages.
The advantages are that it works for any combination of optical properties.