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

摘要

An optical pickup device is provided which includes a double-wavelength objective lens ( 34 ) that collects a light beam selectively emitted from a light-emitting/-detecting element ( 31 ) that selectively emits a plurality of light beams different in wavelength from each other, and also return light from an optical disk ( 2 ), a first diffraction grating ( 45 ) that splits the light beam emitted from a light-emitting/-detecting element ( 31 ) into three beams including a zero-order light beam and positive and negative first-order light beams, a second diffraction grating ( 46 ) that diffracts the return light for traveling along a light path separate from that of the outgoing light, and a third diffraction grating ( 47 ) that corrects a light-path deviation 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 diffracted by the third diffraction element ( 47 ), and a tracking error signal by detecting return portions of the positive and negative first-order light beams from the first diffraction grating ( 45 ).