Objective lens, optical pickup device, and optical disc device
US8599672B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 2012 |
| Grant date | Dec 3, 2013 |
| Priority date | — |
| Expiry date | Aug 31, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2541
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Provided is an objective lens including a diffraction portion provided on a laser beam incident plane or output plane. The diffraction portion includes first second, and third diffraction regions, wherein first laser beams corresponding to a first optical disc having a first transmissive layer are condensed on a data recording portion of the first optical disc, second laser beams corresponding to a second optical disc having a second transmissive layer thicker than the first transmissive layer are condensed on a data recording portion of the second optical disc, and third laser beams corresponding to a third optical disc having a third transmissive layer thicker than the second transmissive layer are condensed on a data recording portion of the third optical disc. An evaluation parameter calculated on the basis of an in-plane efficiency distribution function has a value corresponding to a symbol error rate that is less than a predetermined value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.