Optically Controlled Alignment of Liquid Crystal on Polyimide Films Exposed to Undulator Radiation

Liquid crystal (LC) alignment properties on photo-exposed polyimide films were studied in the UV and VUV regions using linearly polarized synchrotron radiation from the Onuki-type polarizing undulator installed in the electron storage ring NIJI-II in ETL. It was found that the LC alignment uniformity depends on the UV and VUV exposure conditions, especially on the wavelength of the radiation. The photoabsorption spectrum of polyimide films was also measured in both UV and VUV regions. It was concluded that at least two mechanisms exist in the photo-induced alignment of LC molecules on the polyimide films.