Optical head device

摘要

An optical head device includes a plurality of laser light sources emitting laser beams with different wavelengths, a common light receiving element for signal detection which is provided with a light receiving surface, and an optical system which guides the laser beams emitted from the plurality of laser light sources to an optical recording medium and guides return light beams from the optical recording medium to the common light receiving element The optical system includes a diffraction type objective lens which is provided with a plurality of concentrically circular areas for respectively focusing the plurality of laser beams at different positions. The light receiving surface of the light receiving element has an inner region and an outer high density flare region. The light receiving element and the optical system are constructed so that a light receiving part of the light receiving element is located in an inner region not the outer high-density flare region which is generated around the return light beam passing through a center side area in the laser beam using only the center side area of the diffraction type objective lens.