Optical pickup with a diffraction element consist of six regions providing spatial variation corresponding to a focas state
US6909687B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 2001 |
| Grant date | Jun 21, 2005 |
| Priority date | — |
| Expiry date | Dec 21, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0916
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A six-segment holographic surface is divided into regions by dividing lines. A four-segment photodetection part is divided into four photodetection parts equal in area by a section line substantially parallel to the radial direction of an optical disk and a section line orthogonal thereto. A main light beam diffracted in the regions of the six-segment holographic surface are condensed as spots at positions apart from each other on opposite sides on a section line of the four photodetection parts, and the main beam diffracted in the regions is condensed as spots in the center of the photodetection parts of the four-segment photodetection part.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.