Application of a novel photopolymer to a holographic head-up display

Abstract

A novel photopolymer for fabrication of high-resolution volume holograms, which primarily are used on holographic optical elements such as head-up display (HUD), is reported. This photopolymer consists of bisphenol-type epoxy resin and radically polymerizable aliphatic monomer with diaryliodonium salt and 3-ketocoumarin (KCD) as a complex initiator. The chemistry of imaging formation is based on the radical polymerization of the monomer initiated by a holographic exposure, following by the cationic polymerization of epoxy resin by UV-exposure after post-exposure baking. The yellowish color of hologram derived from KCD, the shape of peak of reconstructed light and the blue shift of wavelength of reconstructed light, were improved in order to satisfy the specifications for the combiner of HUD. A stand type holographic HUD system as an example of automotive display attached on the dashboard of an automobile is demonstrated. The display gives a high contrast image, and the combiner has good durability. Copyright © 1999 John Wiley & Sons, Ltd.