Apparatus for reading from and/or writing to optical recording media
US7385905B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 2003 |
| Grant date | Jun 10, 2008 |
| Priority date | — |
| Expiry date | Sep 12, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
When an optical recording medium having a plurality of data layers is being read from and/or written to, the input beam experiences an aberration, inter alia in the top layers of the data layers. In order, nevertheless, to achieve a high data density, a device for correcting the spherical aberration is located in the beam path of the input beam. In the case of the use of an optical diode in which the input beam and the reflected beam have directions of polarization perpendicular to one another, such a device is expensive to implement and associated with a reduced optical efficiency. It is an object of the invention to propose an apparatus for reading from and/or writing to optical recording media, in the case of which a high optical efficiency and balancing of the spherical aberration are achieved with low outlay. For this purpose, the device for correcting the spherical aberration is set up such that the reflected beam traverses it uninfluenced, whereby means for correcting the imaging of the reflected beam onto at least one detector unit are provided in the further beam path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.