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

Abstract

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