Optical information recording/reproducing optical system and optical information recording/reproducing apparatus
US8559290B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 2010 |
| Grant date | Oct 15, 2013 |
| Priority date | — |
| Expiry date | Apr 15, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1376
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical information recording/reproducing optical system where resin material has Tg>115° C., first, second and third films are on an optical disc side of an objective lens and surfaces of an optical element, respectively, a light source side of the objective lens has a fourth film having four or more layers not containing Ti, each of the first, second and third films includes a non-high refractive index layer made of one of silicon oxide, aluminum oxide, aluminum fluoride and magnesium fluoride or a mixture of at least two of them, each of the first, second and third films is not made of one of Ti, Ta, Hf, Zr, Nb, Mo and Cr, a layer of the fourth film closest to a base material is the non-high refractive index layer. The fourth film satisfies 350<λmax(2)<420 and 600<λmin(2)<750, and reflectivity thereof decreases monotonously.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.