Thermo-optical properties of a solar energy storage material

• Published in: Optics and laser technology 1999-09, Vol.31 (6), p.431-435
• Main Authors: El-Kashef, H., Hassan, G.E.
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Interferometers; Optical instruments, equipment and techniques; Physics
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/S0030-3992(99)00091-2

A dual wavelength laser Mach–Zehnder interferometric technique is applied for measuring the absolute values of refractive index n and its thermo-optic coefficients d n/d T for paraffin wax. The values of n and d n/d T are used to calculate a number of the decisive thermo-optic properties. Applying Maxwell’s equation ( ε=n 2) the optical permittivity ε and its thermal coefficient d ε/d T, 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 d n/d λ and dielectric dispersion d ε/d λ are calculated according to Cauchy’s equation. Different important relationships between −d n/d T, −d n/d λ, −d ε/d T and d ε/d λ as a function of wavelength and other important constants are calculated and graphically represented.