Objective lens for optical pick-up
US7038862B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 16, 2004 |
| Grant date | May 2, 2006 |
| Priority date | — |
| Expiry date | Jun 16, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An objective lens that satisfies conditions:−0.02<f1×M1<0.02 (1)−0.02<f2×M2<0.02 (2)−0.29<f3×M3<−0.19. (3)At least one of lens surfaces of the objective lens includes a diffracting structure having a first region for converging the third light beam on a data recording layer of the third optical disc. The diffracting structure within the first region is configured such that a diffraction order at which diffraction efficiency of the first light beam is maximized is a sixth order, a diffraction order at which the diffraction efficiency of the second light beam is maximized is a fourth order, and a diffraction order at which the diffraction efficiency of the third light beam is maximized is a third order.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.