Objective optical system and optical information recording/reproducing device having the same
US7830772B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 2008 |
| Grant date | Nov 9, 2010 |
| Priority date | — |
| Expiry date | Apr 5, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
There is provided an objective optical system for an optical information recording/reproducing device. The objective optical system includes an optical element having an annular zone structure on at least one surface. The annular zone structure includes annular zones configured to have at least one step formed, at a boundary between adjacent ones of the annular zones, to extend in a direction of an optical axis. The at least one step is provided to cause a predetermined optical path length difference between a light beam passing through an outside of the boundary and a light beam passing through an inside of the boundary. The predetermined optical path length difference given to a first light beam by the at least one step is approximately equal to an odd multiple of a first wavelength λa. Abbe number of material of the optical element satisfies a condition of 15<νd<35.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.