Limitations on the use of Fourier analysis to solve the radiative-transfer equation in the small-angle-scattering approximation are discussed. The low-order position and angular spatial frequency components of the transformed scattered radiance are shown to be associated with diffusive multiply scattered radiation, and the high-order components with multiply forward scattered radiation. In addition, qualitative and quantitative comparisons of the theory with numerical and experimental results are given.
L. B. Stotts, "Limitations of approximate Fourier techniques in solving radiative-transfer problems," J. Opt. Soc. Am. 69, 1719-1722 (1979)