Measurement of optical activity using a photoelastic modulator system

Abstract

Adjusting the analyzer at 90 degrees to the strain axis of a photoelastic modulator, one can determine the optical activity by measuring the slope of its DC intensity distribution under various phase modulation amplitudes. This technique was applied to measure the ellipticity of few quartz quarter-wave plates and the optical rotation of an optical active crystal. A multiple reflection enhancement effect in the wave prate was observed and discussed. By considering the photoelastic modulator as an elliptical retarder, we also determined its intrinsic ellipticity and static phase retardation, to increase the accuracy of measurements.