Simple Method of Measuring Alignment Directions and Retardation of Liquid Crystal Cells

概要

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We developed a simple method of measuring alignment directions and retardation of twisted nematic liquid crystal cells. Our method is particularly suitable for the distribution measurement of such cell parameters of the in-plane switching and fringe-field switching panels. The normalized Stokes parameters of light passing through the cell, i.e., $S_{1}$ and $S_{2}$, show a special property wherein a point of $(S_{1},S_{2})$ in the $S_{1}$–$S_{2}$ plane of the Poincaré sphere moves on a circle by rotating the cell. A twist angle and retardation of the cell can be evaluated from the center of the circle separately from an alignment direction at a substrate interface. The alignment direction at the substrate interface can be evaluated by explicit calculation using the evaluated twist angle and an angle between the $S_{1}$-axis and a line from the center of the circle to the point of $(S_{1},S_{2})$.
2007-06-15