Plate aligning
US4340305A · kind A · utility
44Cited by
1References
3Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 26, 1979 |
| Grant date | Jul 20, 1982 |
| Priority date | — |
| Expiry date | Dec 26, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
First and second plates are formed with like periodic patterns. A laser beam illuminates the second plate through the alignment marks of the first plate to provide a pair of diffracted beams that are detected with alignment being indicated when the beams are of the same intensity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.