Patent ID: 7330406
Filing Date: 2008-02-12
Classification: G11B

Abstract:
1. An optical pickup device, comprising: a first light source to emit a first light flux having a wavelength λ a second light source to emit a second light flux having a wavelength λ a collimator lens to collimate the first light flux and/or the second light flux, and an objective lens to converge the first light flux emitted from the first light source on an information recording surface of a first optical information recording medium through a protective layer having a thickness t wherein the collimator lens comprises a diffractive structure, wherein the objective lens comprises a diffractive structure, wherein the objective lens forms a first spot on the information recording surface of the first optical information recording medium by using diffracted light ray generated when the first light flux from the first light source passes through the diffractive structure of the collimator lens and/or the objective lens, and the objective lens forms the second spot on the information recording surface of the second optical information recording medium by using diffracted light ray generated when the second light flux from the second light source passes through the diffractive structure of the collimator lens and/or the objective lens.