Tracking error signal generation using confocally filtered detection
US6563779B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 15, 2000 |
| Grant date | May 13, 2003 |
| Priority date | — |
| Expiry date | Aug 17, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A tracking error signal generation apparatus and method which utilizes confocal detection with a split detector and a differencing circuit for generation of tracking error signals. A first lens is positioned in the path of a light beam returning from an optical medium. A pinhole is positioned in the path of the light beam after the first lens and proximate to the focal plane of the first lens. A second lens is positioned in the path of the light beam after the pinhole, and a split detector, having equal halves is positioned in the path of the light beam after the second lens. A differencing circuit is operatively coupled to each of the halves of the split detector. In operation, a light beam is focused by an optical head onto a track in the optical medium, and the reflection of the beam from the optical medium is directed through the first lens, through the pinhole, through the second lens, and onto the split detector. When the focus of the light beam is centered on the track, the reflected light reaching the split detector is evenly distributed on the two halves of the detector, such that the differencing circuit will generate a tracking error signal (TES) having nominally a zero …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.