Objective lens and optical pickup apparatus

摘要

An optical pickup apparatus includes: a first light source for emitting a first light flux with a wavelength lambda1 for recording and/or reproducing information on a first optical disc having a protective substrate with a thickness t 1 ; a third light source for emitting a third light flux with a wavelength lambda3 for recording and/or reproducing information on a third optical disc having a protective substrate with a thickness t 3 ; and an objective lens arranged in a common optical path of the first light flux and the third light flux when the optical pickup apparatus records and/or reproduces information on each of the first and third optical discs, wherein the first light flux enters into the objective lens as a converging light flux, and a magnification m 3 of the objective lens for a third light flux satisfies - 1/10<=m 3 <0.