Determination of absorption and scattering coefficients for nonhomogeneous media. 2: experiment

Separation of the scattering contribution from the total optical attenuation is necessary to determine the absorption portion of nonhomogeneous media such as naturally occurring minerals. In order to investigate experimentally the applicability of a previously developed two-flux radiative transfer model that takes into account surface reflections and collimated incidence, we have measured pulverized and sintered scattering standards prepared from a glass of known absorption coefficient variation. The new model produces an accuracy improvement up to a factor of 2.5 over the Kubelka-Munk theory. Off-axis scattering measurements were made with improved instrumentation between 0.33 microm and 2.7 microm. The model was then applied to the mineral rhodochrosite in this range to obtain accurate values of scattering and absorption.