A robust polarization-spectral method for determination of twisted liquid crystal layer parameters

Abstract

An experimental method for determining the configurational and optical parameters of the liquid crystal (LC) layers with a twisted structure is proposed. This method provides the determination of the twist angle and orientation of LC structures as well as the spectral dependence of the LC layer retardation. These parameters are estimated from the polarized transmission spectra of LC cell, which are measured using the polarizer-sample-analyzer scheme. In contrast to known methods, the proposed method is insensitive to the presence of moderate anisotropic losses in LC cell (usually, the loss anisotropy is a consequence of the multibeam interference in the thin-layer system including the LC layer); furthermore, the proposed method does not use the small birefringence approximation. The accuracy of the method under various experimental conditions is estimated by numerical modeling.