Objective lens for optical pickup
US6822800B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 2003 |
| Grant date | Nov 23, 2004 |
| Priority date | — |
| Expiry date | Jun 9, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/13922
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective lens for an optical pickup has a single lens element. One surface of the objective lens is divided into a central area and a peripheral area, and a step providing a level difference along a direction of the optical axis is formed at a boundary therebetween. The step provides a phase shift between light passing through the central area and the peripheral area. The level difference is formed such that a thickness on the peripheral area side is greater than a thickness on the central area side at the boundary. In one case, the objective lens satisfies a condition:0.83<hx/hmax<0.97,where hx is a radius of the boundary, and hmax is an effective radius defining a numerical aperture of the surface formed with the step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.