Apparatus for reading a flat record carrier with an optically readable information structure
US4006293A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1975 |
| Grant date | Feb 1, 1977 |
| Priority date | — |
| Expiry date | Apr 16, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0917
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus is described for reading a flat record carrier on which information is stored in an optically readable track-shaped information structure. By the arrangement in the far field of the information structure and at one side of a plane which is formed by the optical axis of an objective system which is used for reading and a line parallel to the center line of the track portion to be read, of a radiation-sensitive detection system which consists of at least two detectors in approximately the position .beta./2, .beta. being the angle at which a first-order beam is diffracted in the lateral direction of the tracks, centering and focussing errors can be detected without the use of auxiliary beams and additional optical elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.