Objective optical element and optical pickup apparatus
US7463568B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 2007 |
| Grant date | Dec 9, 2008 |
| Priority date | — |
| Expiry date | Mar 14, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective optical element of an optical pickup apparatus has a magnification m1 satisfying the following formula for a light flux of the wavelength λ1:−1/7≦m1≦−1/25 and |m1 |<|M1, where M1 is an optical system magnification from the first light source to the first optical information recording medium for a light flux of the wavelength λ1. The objective optical element comprises a common region and an exclusive region. The exclusive region includes an exclusive diffractive structure having a function to suppress an increase of spherical aberration due to a raise of atmospheric temperature. A light flux of a wavelength λ2. having passed through the exclusive diffractive structure intersects with the optical axis at a position different from the position of the converged light spot formed on the information recording plane of the second optical information recording medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.