Patent ID: 7483360

Claim:
An optical pickup comprising: a laser light source; a diffraction grating for splitting laser light emitted from the light source into three light beams which are a main beam as a zeroth order diffracted light beam and two sub beams as ± first-order diffracted light beams; an objective lens for converging laser light onto an information recording surface of an optical disk; a hologram for deflecting return light which travels toward the laser light source after being reflected from the optical disk, by exploiting a diffraction effect; and a light receiving element for receiving the return light deflected by the hologram, wherein the hologram is formed of a polarizing hologram element in which a light component having one given polarization direction is substantially entirely transmitted without being diffracted, whereas another light component having the other polarization direction is diffracted as diffraction light, wherein the hologram is divided into first, second and third deflecting domains, each of which deflecting domains receives the main beam and the two sub beams reflected from the optical disk, the main beams deflected by the first, second and third deflecting domains traveling, in a direction equivalent to a track direction of the optical disk between the two sub beams deflected by a same deflecting domain, the main beam and the two sub beams deflected by the first deflecting domain traveling in the direction equivalent to the track direction of the optical disk between the main and sub beams deflected by the second deflecting domain and the main and sub beams deflected by the third deflecting domain, wherein a light receiving portion of the light receiving element is divided into a first light receiving domain group comprising three light receiving domains for receiving the main beam and the sub beams deflected by the first deflecting domain, a second light receiving domain group comprising three light receiving domains for receiving the main beam and the sub beams deflected by the second deflecting domain, and a third light receiving domain group comprising three light receiving domains for receiving the main beam and the sub beams deflected by the third deflecting domain, and wherein the second and third light receiving domain groups further comprise, respectively, auxiliary light receiving domains disposed adjacent to ends of a light receiving domain which receives the sub beam in a direction perpendicular to the direction equivalent to the track direction of the optical disk.