Photo-patterned e-wave polarizer

• Published in: Displays Vol. 22; no. 1; pp. 27 - 32
• Main Authors: Yip, W.C, Kwok, H.S, Kozenkov, V.M, Chigrinov, V.G
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2001
• Subjects: Lyotropic liquid crystal; Photo-alignment; Polarizer; Polarizer; Lyotropic liquid crystal; Photo-alignment
• ISSN: 0141-9382; 1872-7387
• DOI: 10.1016/S0141-9382(01)00051-8

In this paper, we report our development in the photo-patterned e-wave polarizer. This polarizer is prepared from amphiphilic dye molecules, which self-assemble and stack up to form the hexagonal complexes of lyotropic liquid crystals (LLC) under certain conditions. As a result, it gives rise to a high order parameter and a cylindrical symmetry. Along the c-axis of these complexes most of the e-wave is transmitted, whereas the o-wave, which propagates on the plane orthogonal to this c-axis, can be absorbed effectively. However, the methods usually used to manufacture the e-wave polarizer are based on the mechanical shear flow, which causes unpleasant visual defects and has limited resolution. Therefore, we propose and demonstrate two novel fabrication methods to both photo-align and photo-pattern these e-wave polarizers. The first method consists of transferring a well-prepared LLC polarizing film onto the substrate using the photo-curing glue. The second method consists of applying a photo-alignment layer to induce a preferential orientation of the LLCs. The c-axis in this case is determined by the polarization vector and the incidence plane of the actinic radiation. Since the local structure is patterned optically, the multi-axes and multi-colour polarizers can be prepared cost-effectively. In addition, this photo-patterned polarizing film, which is about 0.3–0.7 μm, can be coated on the internal or external substrate surfaces of a liquid crystal display (LCD). For the TN-LCD with the internal polarizers, we find that the electro-optic characteristics are basically similar to those with the external polarizers. This is central to the internal polarizer development since the STN-LCD is sensitive to any voltage and thickness variations.