Consider a slab consisting of two layers which absorb and scatter light. First the basic differential-integral equation for the intensity of the diffusely reflected light is given, the source being uniform parallel rays. The Memorandum then shows how to determine the nature of each layer using measurements of the light diffusely reflected from the slab. The above is viewed as a nonlinear boundary-value problem and is resolved computationally using the technique of quasilinearization. Numerical examples and FORTRAN programs are provided.