Hewlett-packard Company

Annette C Grot

John S Hoch

Robert C Taber

The hologram card generates a hologram image in response to an illumination light beam. The hologram card comprises a substrate of a first plastic material having a first refractive index. The substrate has a contoured surface. The contoured surface is formed to include localized topological features constituting a diffractive optical element. The diffractive optical element is structured to generate a hologram image when illuminated by the illumination light beam. The hologram card also comprises a protective layer of a second plastic material having a second refractive index that differs from the first refractive index by less than 0.2. The protective layer covers the contoured surface of the substrate. The protective layer is chemically bonded to, and directly contacts, at least the topological features constituting the diffractive optical element.

High-security machine-readable holographic card

An illumination system that comprises a light source, and, disposed in an optical path between the light source and the surface, converging imaging optics, and a diffractive array generator. The diffractive array generator preferably includes a two-dimensional periodic array of multi-level topological features.

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Cupertino, CA, United States of America

Annette C Grot