System for determining the authenticity of an object
US5497227A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 16, 1993 |
| Grant date | Mar 5, 1996 |
| Priority date | — |
| Expiry date | Aug 16, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2019/0629
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Provided is an identification system which is highly effective in identifying the authenticity of an object and extremely difficult to analyze for the purpose of forgery. The object to be identified is affixed with an identification element comprising a reflective layer including a hologram, a diffraction grating or the like, which directs incident light of a prescribed wave length into a plurality of point symmetric directions, and a polarization plane rotating layer which rotates the polarization plane of the light as it passes through the polarization rotating layer. A linearly polarized light is impinged upon the identification element, and is received by a multisegment photodiode arranged in an annular fashion. Those photodiode segments located on one side of a diametric line is covered by a first filter adapted to transmit substantially only the light emitted from the identification element whose plane of polarization is rotated by the polarization plane rotating layer while remaining segments are covered by a second filter adapted to transmit substantially only the light emitted from the identification element whose plane of polarization is not rotated by the polarization pl…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.