Laser measurement of the dielectric constant of insulating liquids

We propose a novel method to measure the dielectric constant of insulating liquids using a laser beam. We use a research ellipsometer composed of a laser source, a polarizer, a compensator, a sample holder, an analyzer, and a photo-detector. The laser beam passes through the oil sample and accordingly undergoes polarization changes of its electric vector components; parallel and perpendicular to the plane of incidence. Through successive adjustment of the polarizer and analyzer azimuthes, two ellipsometric angles are experimentally obtained determining these polarization changes. The electromagnetic model of the oil sample provides the polarization changes as functions of the dielectric constant of the oil sample itself. Therefore, the use of the measured ellipsometric parameters in conjunction with the electromagnetic model, both of the oil sample, gives directly the dielectric constant of the oil sample. Development of the measurement technique, the electromagnetic model, and the expressions for the dielectric constant is briefly presented. Sample experimental measurements using the proposed technique are presented.