Study of the fingerprint-texture formation in cholesteric liquid crystal film

• Main Authors: Fu-Chen Chen, 陳傅丞
• Other Authors: Shu-Hsia Chen
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/01457965387666849139

碩士 === 國立交通大學 === 光電工程所 === 88 === The electric field induced cholesteric liquid crystal phase grating was formed by adjusting the thickness-natural pitch ratio d/p0 and applying voltage. The electric field was a quasi-static field and there was no backflow effect in the film. In this experiment we use two different surface rubbing directions to form fingerprint patterns. Substrates of the film were horizontally aligned by hard rubbing. Angle between the alignment directions of the upper and lower substrates was changed for investigating the stripes direction of fingerprint texture. We found that the rubbing directions on upper and lower substrates can change the direction of phase grating. In addition, the phase grating’s stripe can be changed by external field and LC elastic energy and surface anchoring energy. We also study the polarization characteristic of the light for some diffraction orders in various electric fields.