Refractive Index Measurements of Molten Salts with Wave-Front-Shearing Interferometry

Abstract

A wave-front-shearing interferometer has been used to determine the refractive index of the alkali nitrates LiNO3, NaNO3, KNO3, RbNO3, and CsNO3 from the melting point to a temperature just below the decomposition point. The accuracy of these measurements has been estimated to ±3·10-5 which should be compared with ±3·10–3, being the estimated error in earlier determinations. The refractive index is found to depend almost linearly on temperature. For most of the investigated liquids, however, one gets a better fit to the measured values if a second order dependence is assumed.