Optical pick-up device and objective lens used therein
US6728042B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 22, 2002 |
| Grant date | Apr 27, 2004 |
| Priority date | — |
| Expiry date | Jul 5, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical pickup apparatus comprises two light sources having two wavelengths (&lgr;1<&lgr;2) and a converging optical system having an objective lens. The objective lens comprises a central region; a peripheral region provided at an outside of the central region on at least one optical surface of the objective lens; a diffractive ring-shaped zones which is blazed on a basis of a wavelength &lgr;0 (&lgr;1<&lgr;0<&lgr;2) and is formed on each of the central region and the peripheral region; and a phase difference suppressing structure to suppress a phase difference between a wavefront of a light flux passing the central region and a wavefront of a light flux passing the peripheral region when recording or reproducing information is conducted for the first optical information recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.