Patent ID: 7064900

Claim:
An optical pickup device comprising: a light source that emits a light beam having a predetermined wavelength; an objective lens that focuses the light beam emitted from the light source onto an optical disk and collects return light from the optical disk; a composite optical element including a diffraction element that allows the light beam emitted from the light source to pass through, while diffracting the return light from the optical disk, and a light-path deviation correcting means disposed in a position where the return light diffracted by the diffraction element is incident to correct a light-path deviation of the return light, caused in the diffraction element by a variation in wavelength of the light beam emitted from the light source and direct the return light to a predetermined position; and a light-detecting means for detecting, at a plurality of light-detecting areas thereof, the return light having the light-path deviation thereof corrected by the light-path deviation correcting means, wherein the composite optical element further includes a return-light splitting means disposed in a position where the return light having a light-path deviation thereof corrected by the light-path deviation correcting means is incident to split the return light into a plurality of beams and direct the plurality of beams to the plurality of light-detecting areas of the light-detecting means, wherein the composite optical element is a combination of the diffraction element, light-path deviation correcting means and the return-light splitting means, formed integrally with each other by molding a resin material, wherein the return-light splitting means is a prism having a plurality of flat or curved surfaces, wherein the prism included in the composite optical element is shaped to have the form of a regular-tetragonal pyramid and splits, into four beams, the return light having a light-path deviation thereof corrected by the light-pathdeviation correcting means; and the light-detecting means has the light-detecting area thereof quartered to detect four return light beams, respectively, from the prism included in the composite optical element.