Spherical abberation compensator and optical pickup using the same
US6724710B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 2002 |
| Grant date | Apr 20, 2004 |
| Priority date | — |
| Expiry date | Jul 17, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0948
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A spherical aberration compensator for compensating for spherical aberration resulting from a thickness deviation of a recording medium. The spherical aberration compensator includes a central compensation which provides a phase distribution that is effective for compensating for spherical aberration resulting from the thickness deviation and a peripheral compensation portion which surrounds the central compensation portion and provides a phase distribution that is effective for reducing a worsening of the spherical aberration caused by axial displacement of an objective lens from the central compensation portion. The spherical aberration compensator effectively relieves an optical pickup having an objective lens of an NA of 0.7 or greater of worsening of the spherical aberration resulting from thickness deviation of the recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.