Security device
US5483363A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 15, 1993 |
| Grant date | Jan 9, 1996 |
| Priority date | — |
| Expiry date | Jul 15, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03H2250/40
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A security device includes first and second diffractive structures contained within a surface relief structure. The structures are such that the device responds to illumination at a first, visible wavelength to generate a first, visible pattern while any pattern generated by the second structure is not substantially visible at that wavelength, and the device responds to illumination at a second wavelength substantially different from the first wavelength to generate a second pattern suitable for machine reading while any pattern generated by the first structure is substantially suppressed relative to the machine readable pattern at that wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.