Objective lens and optical pickup device using it
US7286463B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 2004 |
| Grant date | Oct 23, 2007 |
| Priority date | — |
| Expiry date | Jun 8, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective lens is formed as an objective lens element with a diffractive surface on one side. The objective lens focuses a collimated light beam of a first wavelength diffracted by the objective lens onto a first recording medium, a collimated light beam of a second wavelength diffracted by the objective lens onto a second recording medium, and a diverging light beam of a third wavelength diffracted by the objective lens onto a third recording medium. The three light beams are focused at three different working distances from the objective lens and the diffraction orders of the diffracted light of two of the light beams is the same. The objective lens satisfies certain conditions related to the shortest of the three different working distances, the focal length of the objective lens element at the shortest of the three wavelengths, and the thickness of the objective lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.