Patent attributes
This invention is an optical pickup device having a composite optical element (32) which has a first diffraction grating (45) for splitting a light beam emitted from a light source (31) into zeroth-order light, plus-first-order light and minus-first-order light, a second diffraction grating (46) for diffracting the optical path of a return light beam from an optical disc (2), and a split prism (47) arranged at a position where the minus-first-order light diffracted by the second diffraction grating (46) is incident and adapted for splitting the minus-first-order light into a plurality of light beams. It also has a light receiving unit (35) for acquiring a focusing error signal FE by receiving each return light beam split by the split prism (47) and for acquiring a tracking error signal by receiving return light beams from the optical disc (2) of the plus-first-order light and the minus-first-order light split by the first diffraction grating (45).
