Optical pickup device with split hologram element that diffracts light in direction parallel to track

摘要

An optical pickup device includes a light source irradiating a record medium with plural light spots of light emitted therefrom, a plurality of light detecting elelments to which reflected light of the light spots are guided, respectively, to adequately synthesize and compare outputs of said light detecting elements, thereby reading information recorded in tracks of the record medium, and detecting an tracking error and a focusing error, and a hologram element which splits light emitted from the light source into plural beams is disposed in an optical path between the light source and the record medium, said hologram element is split by a split line, said split line elongating in a direction perpendicular to a track of the medium on an optical axis, and a hologram pattern having a diffraction function which is substantially directed in the track direction is disposed on at least one side of said split line, thereby differentiating diffraction conditions on both sides of said split line from each other.