Optical indicia marking and detection system
US4011435A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 1974 |
| Grant date | Mar 8, 1977 |
| Priority date | — |
| Expiry date | Feb 1, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/16
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An optical marking system which utilizes tags that are formed from multiple diffraction gratings, which gratings differ in orientation and number of lines (frequency) in accordance with the coded information desired on the tags. A monochromatic light source illuminates a diffraction grating tag, with reading of the coded information on the tag being accomplished by sensing the reflected light which is projected as images in a Fraunhofer plane. Retroreflective elements are provided in the optic train as a means for stabilizing the direction of reflection from the diffraction gratings such that the reflections are somewhat independent of the tilt angle of the tag with respect to the illuminating light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.