Optical and electrical properties of materials

An interferometric technique using a newly developed Mach–Zehnder interferometer is applied to measure the refractive indices of light transmitting fluids in general. It has been particularly used for determining the refractive indices and its variation with temperature for two solvents of laser dyes (toluene and carbon disulphide). Accuracy of 1×10−5 is achieved where no uncertainity of the measurements arising from the naked eye estimation. The obtained optical results have been used to calculate a number of different physical parameters such as the optical permittivity (or dielectric susceptibility), thermal coefficient of refractive index, temperature coefficient of permittivity, specific refraction, molar refraction, polarizability, radius of the molecule, relaxation time, temperature coefficient of volume expansion, characteristic impedance of matter, and the constant electric moment of a molecule. It is shown that the experimental results agree well with the calculated ones. The advantages of this technique and the sensitivity of the instrument are discussed.