Light source unit, optical detector unit, optical pickup device, and optical disk device

摘要

A light source unit comprises a plurality of light sources emitting a plurality of light beams. A plurality of volume hologram elements are provided for the plurality of light sources respectively, each volume hologram element having a plane of incidence of an incoming light beam and a plane of outgoing radiation of a diffracted light beam which are perpendicular to each other, the plurality of volume hologram elements having mutually different Bragg conditions in which an optical intensity of a diffracted light beam is set to a maximum.