New Rubbing-Free LC Alignment Method using Polarized Pulsed Nd:YAG Laser

摘要

We propose a new alignment method of liquid crystal (LC) utilizing polarized pulsed Nd:YAG laser. The LC alignment was observed on the surface of polyimide (PMDA/ODA) film, irradiated by 4~(th) harmonic wave (266nm) of Nd:YAG laser. The polyimide film exhibited LC alignment capability perpendicular to the electric vector of polarization plane (perpendicular alignment) at small fluence, while at large fluence parallel alignment was observed. We evaluated that the perpendicular alignment at small fluence was caused by the orientation of polymer chains, rather than by the photo-decomposition, and parallel alignment was ascribed to the fabrication of LIPSS (Laser Induced Periodic Surface Structure). The effect of molecular structure of polyimides and exposure conditions - wavelength and atmosphere - is also discussed.