Objective lens, coupling lens, light converging optical system, and optical pick-up apparatus
US6876501B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 2001 |
| Grant date | Apr 5, 2005 |
| Priority date | — |
| Expiry date | Jun 21, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/13727
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective lens for recording and/or reproducing an optical information recording medium, comprises a first lens having a positive refractive power; and a second lens having a positive refractive power; wherein the first lens and the second lens are aligned in this order from a light source side of the objective lens; first lens and the second lens are respectfully made of material having a specific gravity of 2.0 of less and the objective lens satisfies the following conditional formula:NA≧0.70,where NA: a predetermined image side numerical aperture necessary for recording and/or reproducing of the optical information recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.