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 Maxwell’s equation (ε=n2) the optical permittivity ε and its thermal coefficient dε/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/dλ and dielectric dispersion dε/dλ are calculated according to Cauchy’s equation. Different important relationships between −dn/dT, −dn/dλ, −dε/dT and dε/dλ as a function of wavelength and other important constants are calculated and graphically represented.