The Study of Surface Property of Polyimide Liquid Crystal Alignment Thin Films by Means of Reflection Anisotropy Spectroscopy

• Main Authors: Jia-huang Hong, 洪嘉煌
• Other Authors: Wen-jun Zheng
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/66860603693829179667

碩士 === 國立中山大學 === 光電工程學系研究所 === 98 === The purpose of this thesis is to study the relation between surface optical anisotropy of polyimide thin film with different rubbing strength and liquid crystal alignment by means of reflection anisotropy spectroscopy (RAS). We discuss the surface properties of rubbed polyimide thin film by measuring the surface roughness, surface free energy and pretilt angle. RAS is a non-contact optical probe of surfaces. It measures the difference in reflectance of normal incidence linearly polarized light between two orthogonal directions in the surface plane, and we can obtain the surface character of sample by analyzing the signals. It is isotropic of polyimide thin film surface without rubbing, and reflection anisotropy (RA) signal is zero. The non-zero RA signal, i.e. anisotropic of surface, is revealed because of rubbed polyimide thin film surface. The RA signal is increasing with an increase in rubbing strength. In the results, we found that the pertilt angle is increasing with a decrease in surface free energy, and discovered the correlation between RA signal strength of characteristic wavelength and pretilt angle of liquid crystal at the rubbed polyimide thin film.