Thermo-optical properties of a solar energy storage material

A dual wavelength laser Mach–Zehnder interferometric technique is applied for 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 Maxwellʹs equation (epsilon=n2) the optical permittivity epsilonand its thermal coefficient depsilon/dT, specific refraction, specific dispersivity, polarizability per unit volume and the ratio of atomic to electronic polarizabilities are calculated. On the other hand the optical dispersion dn/dlambda and dielectric dispersion depsilon/dlambda are calculated according to Cauchyʹs equation. Different important relationships between -dn/dT, dn/dlambda, -depsilon/dT and d epsilon /dlambda as a function of wavelength and other important constants are calculated and graphically represented.