Patent ID: 7577077
Filing Date: 2009-08-18
Classification: G11B

Abstract:
1. An optical pickup apparatus, comprising: a first light source to emit a light flux of a wavelength λ a second light source to emit a light flux of a wavelength λ a third light source to emit a light flux of a wavelength λ an objective optical element into which an infinite parallel light flux comes when recording and/or reproducing information is conducted for the first, second and third optical information recording mediums; wherein the objective optical element comprises a first diffractive structure; wherein a converged-light spot is formed on the first optical information recording medium with m-th order (m is a natural number) diffracted-light ray of the wavelength λ a converged-light spot is formed on the second optical information recording medium with n-th order (n is a natural number) diffracted-light ray of the wavelength λ a converged-light spot is formed on the third optical information recording medium with k-th order (k is a natural number) diffracted-light ray of the wavelength λ wherein one of m, n and k is different from one of other two numbers, and wherein the light flux of the wavelength λ wherein the objective optical element comprises a different diffractive structure which is farther from the optical axis of the objective optical element than the first diffractive structure and wherein the diffraction order number of the light flux of the wavelength λ