Patent ID: 7660225
Filing Date: 2010-02-09
Classification: G02B,G11B

Abstract:
1. An objective lens for use in an optical pickup apparatus, the optical pickup apparatus comprising: a first light source for emitting a first light flux with a first wavelength λ a second light source for emitting a second light flux with a second wavelength λ a converging optical system comprising an objective lens; and a photodetector, wherein the optical pickup apparatus reproduces and/or records information for a first optical information recording medium having a protective layer with a thickness t the objective lens comprising: wherein the objective lens has a single lens structure, and the central area comprises a diffractive structure in which a diffraction order providing a maximum efficiency for each of the first light flux and the second light flux is a same each other, and a phase structure providing a same amount of optical path difference for each of the first light flux and the second light flux.