High-Speed Simultaneous Measurements of Cell Thickness and Twist Angle in Reflective Liquid Crystal Display Panels by Using a Liquid-Crystal Polarization Converting Device

Abstract

We propose an optical measurement method for simultaneously determining the cell thickness and twist angle in reflective liquid crystal (LC) cells by using an LC polarization controlling device such as a circularly-homogeneously aligned LC (CH-LC) cell and a charge couple device camera. Since the minimum point of the spatial light intensity distribution at two wavelengths from the reflective LC cell is measured through the CH-LC cell, and then both of the cell thickness and twist angle can be derived by the Jones matrix analysis.