Document card containing information in holographic form
AssigneeInternational Business Machines Corporation
InventorsPierre R. Chevillat, Fritz Gfeller
Life of this patent
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Abstract
An identification card provided with secret data contained in the form of a wave guide hologram recorded in a layer on the card. Light for developing or displaying the hologram is introduced into a wave guide layer extending along the surface of the card through a grating that admits light only of a given wave length suitable for developing the wave guide hologram. The secrecy of the wave guide hologram is further enhanced by incorporating into the light coupling grating a further hologram by which light only of a predetermined pattern can be coupled to the wave guide for delivery to the wave guide hologram.
Claims5
A document form comprising a base, a transparent layer overlying said base and forming an optical waveguide defining an elongated light path extending parallel to said base, an image layer contiguously overlying said transparent layer and containing, at a first location along said light path, at least one hologram that is developable in response to light of a given wave length traveling through said wave guide, and means, located at a second location along said light path, for coupling only light of said given wave length from outside said card into said transparent layer, said coupling means comprising a further hologram of a unique light source pattern whereby only light of said unique light source pattern can be coupled to said transparent layer.
Dependencies are inferred from the claim text.