Development of a compact broadband circular dichroism spectropolarimeter for circular polarizer applications

Abstract

A compact circular dichroism (CD) spectropolarimeter is demonstrated in this study. The system utilizes liquid crystal polarization gratings (LCPGs) and mini spectrometers to analyze the ellipticity spectra of polarized light. The residual spectra of the LCPG from the opposite diffraction order are subtracted to improve measurement accuracy by almost one order of magnitude. The novel CD spectropolarimeter is applied to inspect the quality of a commercial circular polarizer (CP), and the results are compared with those obtained with a commercial CD spectropolarimeter. The measurement accuracy of our system is determined to be around 0.3°. The results show that our design is feasible to produce a compact and low-cost CP inspection apparatus.