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Knowledge of the optical constants of particulate samples is critical in order to accurately model their optical behavior. For example, the dispersion and attenuation of a silicate sand are required to model scattering through a dust cloud. Most methods of measuring these quantities, however, require a polished solid sample and are therefore not suited to particulates. We present a novel method of measurement based on spectroscopic ellipsometry that can be applied to any particulate material. First, an adhesive compound is prepared and polished, and its optical constants are extracted. Then, a mixture of the adhesive and a particulate sample is prepared, and, treating the mixture as a Bruggeman effective medium, the optical constants of the particulate material are determined. We test the method’s effectiveness using pure silica powder, demonstrating that the results match literature values. The method is then applied to real sand samples. We present data for several types of sand and show that it is possible to accurately determine their optical properties and to observe the Christiansen effect in these samples.
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