| Summary: | 碩士 === 逢甲大學 === 電機工程所 === 97 === Nematic liquid crystal cells are widely applied in liquid crystal displays (LCDs) and related electro-optical devices. The cell parameters, such as the pretilt angle, cell gap and polar anchoring strength, directly affect the quality and performance of products. Therefore, this work presents a simple method to simultaneously determine the pretilt angle and cell gap of nematic liquid crystal cells. The phase retardation of nematic liquid crystal cells can be measured precisely by the heterodyne interferometry with only two appropriate incident angles. Then, the pretilt angle and cell gap can be determined. In experiment, the cells with pretilt angles in different ranges were measured, including a homogeneously aligned cell, a vertically aligned cell, and a liquid crtstal cell with an intermediate pretilt angle in the range of 30�{60�a. The measured results are in good agreement with the reference data which were measured using the commercial Mueller matrix polorimeter. Furthermore, with the same setup, the polar anchoring strength of homogeneously aligned cell was measured by applying voltages to the cell. The characteristics were also simulated with DIMOS software. The proposed method has the advantages of simplicity of installation, ease of operation, high stability, high accuracy, and high resolution. In particular, this method has no restriction on the range of pretilt angle.
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