A direct determination technique for azimuth alignment in photoelastic modulation ellipsometry

Abstract

Instead of the nulling method, a three-intensity-measurement technique is proposed to determine the azimuth deviation of the polarizer (P), photoelastic modulator (PEM) and analyzer (A) with respect to the specimen surface for ellipsometric measurements. After the initial alignment in a straight-through setup, we adjusted the azimuth of P at 45 degrees to the strain axis of the PEM. Arranging a Polarizer-PEM-Sample-Analyzer ellipsometer by subjecting a specimen at the required incident angle, we measured a set of three DC radiances at the zero point of the zero-order Bessel function. In addition to the azimuth deviation, the ellipsometric parameter can also be determined from the same measurements.