Thermo-optical properties of a solar energy storage material

A dual wavelength laser Mach-Zehnder interferometric technique is applied f or measuring the absolute values of refractive index n and its thermo-optic coefficients dn/dT for paraffin wax. The values of n and dn/dT are used to calculate a number of the decisive thermo-optic properties. Applying Maxwe ll's equation (epsilon = n(2)) the optical permittivity epsilon and its the rmal coefficient d epsilon/dT, specific refraction, specific dispersivity. polarizability per unit volume and the ratio of atomic to electronic polari zabilities are calculated. On the other hand the optical dispersion dn/d la mbda and dielectric dispersion d epsilon/d lambda are calculated according to Cauchy's equation. Different important relationships between -dn/dT, -dn /d lambda, -d epsilon/dT and d epsilon/d lambda as a function of wavelength and other important constants are calculated and graphically represented. (C) 2000 Elsevier Science Ltd. All rights reserved.