The hologram recording sheet according to the invention is made up of a base film and hologram sensitive materials sensitive to different wavelength regions formed therein in a desired pattern, or a film and at least two hologram recording sensitive materials sensitive to different wavelength regions...http://www.google.ca/patents/US7579119?utm_source=gb-gplus-sharePatent US7579119 - Hologram recording sheet, holographic optical element using said sheet, and its production process
