Security blank with enhanced authenticating features, and a method and an apparatus for determining the genuineness of the security blank
US4537504A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 25, 1982 |
| Grant date | Aug 27, 1985 |
| Priority date | — |
| Expiry date | Jan 25, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/16
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A security blank is formed with a light-redirecting spatial structure including a deterministic component establishing at least one authenticating feature, and a stochastic component superimposed on the deterministic component, and sufficiently obscuring the deterministic component so as largely to frustrate recognition of the function of the authenticating feature by intensity measurement of light reflected therefrom. Recognition of the function of the authenticating feature is made possible by a method and an apparatus measuring the degree of coherence of two narrow bundles of light rays obtained from light reflected from the spatial structure upon its illumination by light of a selected wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.