We have obtained a sufficient condition under which the ladder approximation may be used to decouple the moment equations (e.g., the Bethe-Salpeter equation) that result when one analyzes the propagation of pptical waves in a randomly inhomogeneous medium. Simply stated, this means that the mean free path for multiple scattering by the inhomogeneities is required to be large in comparison with the size of the inhomogeneities.
© 1982 Optical Society of America
Ronald L. Fante, "Sufficient condition for applying the ladder approximation to the multiple scattering of light in random media," J. Opt. Soc. Am. 72, 815-817 (1982)