OPTICAL HEAD DEVICE

PROBLEM TO BE SOLVED: To provide an optical head device in which light quantity distribution is corrected by dispersion. SOLUTION: The optical head device includes: a laser beam source; a polarization beam splitter; a photodetector for monitoring light quantity; a detector for signal light; and a space division phase difference element which includes a first region being a center region including an optical axis and a second region which is formed around the first region and which emits light of a polarization state being different from a polarization state of light emitted from the first region, and in which at least one side of the first region and the second region is formed by a double refraction material. In the optical head device, light from the laser beam source is made incident on the space division phase difference element, a part of the light emitted from the first region in the space division phase difference element is polarized by the polarization beam splitter and is made incident on the photodetector for monitoring light quantity, the other of the light emitted from the first region and light emitted from the second region are transmitted through the polarization beam splitter, and applied to the optical disk, and reflected light from the optical disk is made incident on the detector for signal light. COPYRIGHT: (C)2011,JPO&INPIT