title: Electrically switchable liquid crystal Fresnel lens using UV-modified alignment film.
abstract: A simple method to make a switchable liquid crystal (LC) Fresnel lens with high diffraction efficiency and a low driving voltage was proposed based on the photo-induced surface modification of the vertical alignment layer. UV illumination alters the pretilt angle of alignment layers, a Fresnel zone-distribution hybrid alignment in the homeotropic LC cell can be straightforwardly achieved through UV exposure, yielding a concentric structure of the Fresnel phase LC lens. A remarkable diffraction efficiency of ~31.4%, close to the measured diffraction efficiency of the used Fresnel-zone-plate mask of 32%, was detected using a linearly polarized incident beam.
authors.affiliation: Institute of Imaging and Biomedical Photonics, National Chiao Tung University, Tainan 711, Taiwan.
authors.forename: Shie-Chang
authors.initials: SC
authors.lastname: Jeng
authors.forename: Shug-June
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Jing-Shyang
authors.initials: JS
authors.lastname: Horng
authors.forename: Kuo-Ren
authors.initials: KR
authors.lastname: Lin
mesh_terms: D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D050866:Liquid Crystals / Q000737:chemistry* / Q000528:radiation effects; D008567:Membranes, Artificial; D008968:Molecular Conformation / Q000528:radiation effects; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014466:Ultraviolet Rays
chemical_list: D008567:Membranes, Artificial