Optically-based methods and apparatus for performing sorting, coding and authentication using a gain medium that provides a narrowband emission
US6832783B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 25, 2002 |
| Grant date | Dec 21, 2004 |
| Priority date | — |
| Expiry date | Nov 25, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/1205
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Disclosed are methods and apparatus for at least one of authenticating, sorting or counting documents, as well as to security structures contained within documents and to documents containing security structures. A security device or structure includes an optical gain medium and a structure having boundaries that impart an overall geometry to the structure that, in combination with at least one material property of the structure, supports an enhancement of electromagnetic radiation emitted from the gain medium for favoring, in one embodiment, the creation of at least one mode that enhances an emission of electromagnetic radiation within a narrow band of wavelengths. Suitable, but not limiting, shapes for the structure comprise elongated, generally cylindrical shapes such as filaments, a sphere shape, a partial-sphere shape, a toroidal shape, a cubical and other polyhedral shape, and a disk shape. The structure is preferably comprised of at least one of a monolithic structure or a multi-layered structure or an ordered structure that may provide for distributed optical feedback. In a preferred embodiment of this invention the security device forms a part of a currency, a passport, a …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.