Hidden Holograms and uses thereof
US5838466A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 1996 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Dec 13, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S283/903
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Replicas of a surface relief hologram, or other light diffraction pattern, are coated with a transparent material having substantially the same refractive index as the holograms to conform to the surface relief patterns and thus hide the hologram. The coating is pealed by hand off of the surface relief pattern in order to reveal an image visible in light reflected from the hologram. Such hidden holograms can be attached to a greeting card to reveal a greeting when the coating is removed, attached to pages of magazines or books to carry an advertising message, and the like. Other uses include making lottery tickets or other indications of a prize from such holograms, since the indication of any prize won by the holder remains hidden until the coating is pulled off, even though the coating is optically transparent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.