Patent ID: 6824929
Filing Date: 2004-11-30
Classification: G03H

Abstract:
A method for copying a hologram comprising:(a) placing a photosensitive element in contact with an outer surface of a holographic element; the holographic element comprising an optically transparent layer disposed adjacent a master hologram; the optically transparent layer comprises glass and the surface of the optically transparent layer opposite the master hologram comprises the outer surface of the holographic element, wherein the outer surface comprises an etched surface incorporated directly into the surface of the optically transparent layer; the photosensitive element comprising a photosensitive layer disposed adjacent a cover sheet, wherein placing step is performed by placing the outer surface of the holographic element in contact with the surface of the cover sheet opposite the photosensitive layer; and (b) exposing the photosensitive element and the holographic element to a coherent light beam whereby a replicate of the hologram is formed in the photosensitive element; characterized in that the placing step is performed with the outer surface of the holographic element having a matte surface with a surface roughness measured by profilometry in the range from 5 to 200 nanometers and has a specular reflectance of at least five percent.