Method and apparatus for inspection of security articles incorporating a diffractive optical projection element
US7652757B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 10, 2005 |
| Grant date | Jan 26, 2010 |
| Priority date | — |
| Expiry date | Jul 29, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/0032
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A method and apparatus for inspection of a security article (10) is provided in which a substantially collimated light beam (15) from a point light source (14) is directed onto a diffractive optical projection element (DOE) (11). The light beam is transformed by the DOE (11) into a patterned beam (17) which is reconstructed to form a projected image at a particular position in space remote from the surface of the security article 910). An optical detection device 916) is located at which the patterned beam (17) is reconstructed to detect the projected image. The inspection method and apparatus may be used in equipment for handling, sorting, counting or otherwise processing security articles, in particular security documents such as banknotes. The apparatus may include a processor for generating a signal when the absence or poor quality of a DOE is detected and which is used to isolate or mark the security article.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.