Optical focussing device
US4023033A · kind A · utility
68Cited by
6References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1976 |
| Grant date | May 10, 1977 |
| Priority date | — |
| Expiry date | Sep 29, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0909
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A device for focussing a read-out light beam on a moving data carrier. It comprises an objective lens which causes said read-out beam to converge on the data carrier; a cylindrical lens arranged in the path of a light beam reflected by the data carrier; and photo-electric means for detecting the reflected beam and arranged in such a fashion that the light spot obtained there, normally substantially circular in shape, is distorted by elongation if focussing of the read-out beam on the data carrier is incorrect.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.