Optical pickup device capable of detecting a stable error signal

摘要

An optical pickup device employing a signal detection unit including a hologram element (10) having a plurality of pattern regions for diffracting and/or focusing light reflected and incident from a recording medium, a photodetector (30) having a plurality of light receiving regions for receiving and photoelectrically converting the light diffracted by the hologram element and a signal operation unit (50) for generating a focus error signal and/or a track error signal from a signal detected from the photodetector (30). The optical pickup device can implement a stable servo operation even at deviations of the photodetector, a change in the wavelength of light emitted from the light source, and/or shift of focusing means such as an objective lens, and can record and/or reproduce high-density information on/from the recording medium. <IMAGE>