High-security machine-readable holographic card
US6005691A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 11, 1996 |
| Grant date | Dec 21, 1999 |
| Priority date | — |
| Expiry date | Dec 11, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S283/904
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.