Tracking servo system for controllably projecting an optical beam on an optical disk
US4782474A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 1986 |
| Grant date | Nov 1, 1988 |
| Priority date | — |
| Expiry date | Jan 30, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/09
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical storage apparatus for storing and reading information on an optical disk with an optical beam, including a tracking servo system having an objective lens, which is driven in a focusing direction F and a tracking direction T by a lens actuator, and a tilting mirror, which is rotated by a mirror actuator. The tracking servo system eliminates beam shift by controlling the lens actuator and the mirror actuator to position the lens and the mirror so that the laser beam always passes through a back focal point of the lens located on the opposite side of the lens from the optical disk. As a result, the laser beam proceeds from the lens to the disk along a path which is parallel with the optical axis of the lens and strikes the disk perpendicularly. Accordingly, the return path of the laser beam reflected by the surface of the disk coincides with the incident path of the laser beam, and no beam shaft is experienced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.