Optical information recording/reproducing optical system and optical information recording/reproducing apparatus
US8305865B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 2010 |
| Grant date | Nov 6, 2012 |
| Priority date | — |
| Expiry date | Jun 4, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1374
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective lens for an optical information recording/reproducing optical system for an optical disc letting a laser beam impinge on a recording layer of the optical disc, and wherein a center wavelength λ (unit: nm) of the laser beam is in a range defined by a condition: 390≦λ≦420, a base material of the objective lens is made of resin, the resin has a glass transition temperature Tg and light transmissivity T (unit: %) per a path length of 3 mm at a wavelength of 406 nm defined by conditions: Tg≧115° C., 85≦T≦90, same antireflection films or different types of antireflection films are respectively formed on optical surfaces of the objective lens, and each of the antireflection films formed on the objective lens has a thickness of 100 nm or more in a vicinity of an optical axis of the objective lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.