Optical pick-up
US6760295B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 29, 1999 |
| Grant date | Jul 6, 2004 |
| Priority date | — |
| Expiry date | Dec 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/13727
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical pick-up includes light sources for emitting light beams having different wavelength, the light sources being switched according to the kind of optical discs, a refractive lens element for converging the light beams from the light sources onto recording layer of the optical disc; and a spherical aberration correcting element on which a concentric phase grating structure is formed, the phase grating structure altering spherical aberration in response to change of wavelength to correct change of the spherical aberration due to change of the thickness of the cover layer. The spherical aberration correcting element has a wavelength dependence such that spherical aberration varies in the undercorrected direction as wavelength of incident light increases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.