Calibration-Free Multichannel Ellipsometry for Retardance Measurement

Abstract

When rotating sample configurations are adopted in transmission ellipsometry, the retardance of a sample can be measured without a calibration process to find the azimuths of optical elements. Two configurations are employed: (1) rotation of sample between polarizer and analyzer whose transmission axes are fixed in parallel; (2) dual rotations of sample and compensator between polarizer and analyzer. The former is simple in design. Meanwhile, the latter shows high sensitivity for low retardance. As the transmission axes of both polarizer and analyzer are fixed in these configurations, any errors related to the source polarization or polarization sensitivity of the detector can be avoided. Moreover, both systems are easy to construct, because complicated electronics are not required to control the azimuths of optical elements. By using a multichannel detection system, retardance over 300 to 800 nm can be measured in a simple and fast way.