Polarization modulated transmission spectro-ellipsometry

A polarization modulated transmission spectro-ellipsometer (PMTSE) features high sensitivity for retardation and high-speed data acquisition. Although optical servo control of a photoelastic modulator (PEM) has improved the accuracy of the system, the residual birefringence mainly of the PEM hinders detection of minute retardation. We have installed a compensator in order to cancel out the residual birefringence and realized base line shift that is within 0.2% of full scale. Optical anisotropies are formulated in the Mueller matrices. Accuracy for a large signal was verified from measurements of a sheet polarizer and a quartz rotator. Detectability was ascertained from the retardation spectrum, <1 nm, of a amorphous poly-olefin film and aqueous solution of a chiral metal complex, Δ−[Co(en)3]3+, whose peak signal magnitude is <1% of full scale. A time resolution of 1 ms was utilized in the dynamic response measurement of a liquid crystal, 5CB, that had a response time of 3–4 ms.