Determination of Orientational Distribution of Side Chains of Polyimide Layer for Liquid Crystal Alignment by Surface Second-Harmonic Generation

Abstract

We have determined the orientational distribution function (ODF) of the side chain polyimide (PI) films used for liquid crystal alignment. The second-harmonic generation (SHG) in four sample geometries were measured as a function of polarizer rotation angle. To determine ODF, we developed a new fitting method of the five layer model using the maximum entropy method. We found that the ODF of the side chains of PI film of the air-side surface is quite different from that of the substrate side.