Patent ID: 7075880
Filing Date: 2006-07-11
Classification: G11B

Abstract:
1. An optical pickup apparatus, comprising: a light source unit in which a first light source to emit a first light flux having a wavelength λ a converging optical system to conduct recording or reproducing information for an information recording plane of a first optical information recording medium having a first protective base plate having a thickness t wherein the converging optical system comprises, a coupling lens into which the first light flux emitted from the first light source or the second light flux emitted from the second light source proceed to be incident; an objective lens to converge the first or second light flux having passed through the coupling lens on the information recording plane of the first or second optical information recording medium; and a diffractive structure which is structured such that a focal length of the first light flux from the first light source passing through the diffractive structure is different from a focal length of the second light flux from the second light source passing through the diffractive structure, wherein the diffractive structure is provided on at least one optical surface of the coupling lens.