Optical pickup device and optical disk device and optical device and composite optical element

摘要

An optical pickup device is provided which includes a first diffraction grating ( 45 ) that splits a light beam emitted from a light-emitting/-detecting element ( 31 ) into a zero-order light beam and positive and negative first-order light beams, a second diffraction grating ( 46 ) that diffracts return light from an optical disk ( 2 ) for traveling along a light path separate from that of the outgoing light, and a third diffraction grating ( 47 ) that corrects the deviation of the light path by diffracting the positive first-order light beam diffracted by the second diffraction grating ( 46 ). The light-emitting/-detecting element ( 31 ) provides a focusing error signal FE by detecting the negative first-order light beam, and a tracking error signal by detecting return portions of the positive and negative first-order light beams from the first diffraction grating ( 45 ).