Formation of Reflection-type Hologram by Means of Polymer Azobenzene Liquid Crystal Films

Abstract

This study describes formation of reflection-type holograms in polymer liquid crystals (PLCs) containing a photochromic moiety (azobenzene) and a mesogenic unit (tolane). Three-dimensional (3-D) images were recorded with linearly polarized Ar ion laser beams at 488 nm. We investigated the spatial frequency in image storage to produce the optical recording media with a high storage density. It was found that clear images of 3-D objects were recorded. A maximum value of the spatial resolution, which was calculated from an incident angle of writing beams reached more than 5000 lines/mm. These stored images remained unchanged after 6 months when the films were preserved at room temperature. It can be assumed that mechanism of image storage is based on change of refractive index of PLCs with trans-cis photoisomerization of azobenzene moiety.