Application of DuPont photopolymer films to automotive holographic display

摘要

Abstract: Automotive holographic head-up display (HUD) systemsemploying DuPont holographic photopolymer films arepresented. Holographic materials for automotiveapplication are exposed to severe environmentalconditions and are required high performance. Thispaper describes the improvement of DuPont photopolymerfilms for the automotive use, critical technical issuessuch as optical design, external color and stray light.The holographic HUD combiner embedded in a windshieldof an automobile has peculiar problems called externalcolor. Diffraction light from holographic combinermakes its external color tone stimulative. We haveintroduced RGB three color recording and colorsimulation in order to improve the external color. Amoderate external color tone was realized by theoptimization in terms of wavelengths and diffractionefficiencies of the combiner hologram. The stray lightcalled flare arises from a reflection by glass surfaceof windshield. We have developed two techniques toavoid the flare. First is a diffuser type trap beamguard hologram which reduces the intensity of theflare. Second is the optimization of the design ofhologram so that the incident direction of flare islower than the horizon line. As an example ofautomotive display a stand-alone type holographic HUDsystem attached on the dashboard of an automobile isdemonstrated, which provides useful driving informationsuch as route guidance. The display has a very simpleoptical system that consists of only a holographiccombiner and a vacuum fluorescent display. Its thinbody is only 35 mm high and does not obstruct driver'sview. The display gives high contrast and wide image.!14