Disclosed is an apparatus and method of illuminating an image display via an electrically switchable holographic optical element. The method includes a first electrically switchable holographic optical element (ESHOE) receiving illumination light. The first ESHOE comprises oppositely facing front and...http://www.google.fr/patents/US6317228?utm_source=gb-gplus-shareBrevet US6317228 - Holographic illumination system
