Optical pickup apparatus having diffractive element for focusing and tracking plurality of light types

摘要

There is provided an optical pickup apparatus. In an optical pickup apparatus, a focus diffraction region includes focus regions of which a number of types is equal to a number of types of light that can be emitted by a light source. The types of the focus regions correspond to the respective types of light, the respective focus regions diffract the corresponding types of light toward same positions of focus light-receiving regions. The focus regions include a plurality of focus segmented regions. The plurality of focus segmented regions of the respective types of focus regions are periodically distributed in the focus diffraction region, and at least some of the focus segmented regions are disposed to be adjacent to focus segmented regions for different types of light.

主权项

1. An optical pickup apparatus comprising:
a light source capable of emitting a plurality of types of light having different wavelengths, an optical recording medium being irradiated with the plurality of type of light; a light-receiving element having a plurality of light-receiving regions, some of the plurality of light-receiving regions being used as focus light-receiving regions for a focus servo; and a diffraction element having a focus diffraction region for diffracting at least a part of light which is emitted by the light source and reflected by the optical recording medium, toward the focus light-receiving regions, the focus diffraction region including focus regions of which a number of types is equal to a number of the plurality of types of light that can be emitted by the light source, the types of the focus regions corresponding to the plurality of types of light, the respective focus regions diffracting the corresponding types of light toward same positions or vicinities of the focus light-receiving regions, and the focus regions including a plurality of focus segmented regions which are distributed in a periodic manner, at least some of the focus segmented regions being disposed to be adjacent to focus segmented regions for different types of light, the plurality of light-receiving regions including a first light-receiving region and a second light receiving region, the first light-receiving region being disposed between the diffraction element and the focus light-receiving regions as viewed from an optical axis direction of the diffraction element, and the second light-receiving region being disposed on the opposite side of the first light-receiving region with respect to the focus light-receiving regions as viewed from the optical axis direction of the diffraction element.