Patent ID: 7525879
Filing Date: 2009-04-28
Classification: G11B

Abstract:
1. An objective optical element for use in an optical pickup apparatus including a first light source emitting a first light flux with a first wavelength λ1for recording and/or reproducing information on an information recording surface of a first optical information recording medium having a protective layer with a thickness t1, a second light source emitting a second light flux with a second wavelength λ2 (λ1 <λ2) for recording and/or reproducing information on an information recording surface of a second optical information recording medium having a protective layer with a thickness t2 (t1≦t2), a third light source emitting a third light flux with a third wavelength λ3 (λ2 <λ3) for recording and/or reproducing information on an information recording surface of a third optical information recording medium having a protective layer with a thickness t3 (t2 <t3), and a light converging optical system including an objective optical element, the objective optical element comprising: