Optical information recording /reproducing device and objective lens for the same
US7843792B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 2007 |
| Grant date | Nov 30, 2010 |
| Priority date | — |
| Expiry date | Feb 7, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
There is provided an objective lens including a first optical member and a second optical member which are made of materials different from each other and are cemented together at a cementing surface. The cementing surface includes a first phase shift structure having a plurality of refractive surface zones concentrically formed about an optical axis of the objective lens. The first phase shift structure satisfies conditions (1) and (2):0.85<Φ2/Φ1<1.15 (1)0.10<|(Φ3−Φ2)/Φ1|<0.50 (2)where Φ1=m(λ1)×(λ1/(n2(λ1)−n1(λ1))), Φ2=m(λ2)×(λ2/(n2(λ2)−n1(λ2))), Φ3=m(λ3)×(λ3/(n2(λ3)−n1(λ3))), m(λ1), m(λ2), and m(λ3) are diffraction orders at which diffraction efficiencies of the first through third light beams are maximized, respectively, n1 (λ1), n1 (λ2), and n1 (λ3) are refractive indexes of the first optical member, respectively, and n2 (λ1), n2 (λ2), and n2 (λ3) are refractive indexes of the second optical member, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.