In system for creating reading and writing on rotatable information storage media, an apparatus for multilayer source positioning using the laser source as a detector
US5892739A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 13, 1998 |
| Grant date | Apr 6, 1999 |
| Priority date | — |
| Expiry date | Feb 13, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/13727
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A laser beam is split into two beams. One beam is oscillatorily varied at a first frequency in a direction associated with control of beam focus within two or more layers of a rotatable information storage medium. The second beam is oscillatorily varied at a second (different) frequency in a direction so that it moves back and forth across an edge of a reference track. In the embodiment herein both beams, after reflection from the medium, are returned to the laser source which is also used as a photodetector. Separate filters are used to examine the electrical output of the photodetector/source so as to simultaneously control positioning of the laser light source along the axes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.