Obtaining material absorption properties from remission spectra of directly illuminated, layered samples

The effective linear absorption coefficient, K, obtained in transflection from directly illuminated samples made up of layers of thickness d, may be approximately related to the linear absorption coefficient, k, of the material making up the layers through the following empirical equations: k = [(1 - 1/2 exp(-2Kd)] K and K = [(1 + exp(-4kd)] k. The fractions of incident intensity absorbed or remitted by one layer may be modeled by assuming that that the light that moves through a sample has both the characteristics of directed and diffuse radiation.