Patent ID: 8004954
Filing Date: 2011-08-23
Classification: G11B

Abstract:
1. An optical pickup comprising: a first light source that emits light of wavelength λ a second light source that emits light of wavelength λ a third light source that emits light of wavelength λ an objective lens that focuses light of wavelength λ a detector that detects light reflected by the optical disk; and a diffraction aperture element that transmits or diffracts the light emitted by the light sources and the light reflected by the optical disk, wherein the diffraction aperture element has a first diffraction region of annular configuration whose an inner radius is R the first diffraction region is divided into a plurality of first regions by the direction of diffraction, while the direction of diffraction of the divided first region is different from the direction of diffraction of the first region that is located at a position disposed symmetrically thereto with respect to the optical axis, and the second diffraction region is divided into a plurality of second regions by the direction of diffraction, while the direction of diffraction of the divided second region is different from the direction of diffraction of the second region that is located at a position disposed symmetrically thereto with respect to the optical axis.