Optical head, recording and/or reproducing method and apparatus and method for detecting thickness
US6418108B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 7, 1999 |
| Grant date | Jul 9, 2002 |
| Priority date | — |
| Expiry date | Jan 7, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10532
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical head used for recording/reproducing information signals for an optical disc having a light transmitting layer on a recording layer includes an actuator for the collimator lens. A collimator lens arranged between a light source and an objective lens is moved by the actuator for the collimator lens in a direction of cancelling the spherical aberration ascribable to thickness errors in the light transmitting layer. By this structure, the amount of generation of spherical aberration is reduced even if the numerical aperture NA of the objective lens loaded on the optical head is increased to render it possible to increase the recording capacity of the optical disc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.