Patent ID: 8406102

Claim:
An optical pickup that writes data on a track on an optical storage medium and reads the data being written on the track in parallel, the optical pickup comprising: a light source configured to emit a light beam; a first diffractive element configured to diffract light that is polarized in a particular direction and split the light beam that has been emitted from the light source into a plurality of light beams including a write beam and a read beam; an objective lens configured to converge the write beam and the read beam onto the same track on the optical storage medium; a lens actuator configured to shift the objective lens to perform a focus control and a tracking control so that the magnitude of shift of the objective lens from its initial position as measured in a tracking direction has an upper limit of 0.3 mm to 0.6 mm; a wave plate that is arranged between the first diffractive element and the optical storage medium and that is designed so that the polarization direction of light going from the first diffractive element toward the wave plate is perpendicular to the polarization direction of light going from the wave plate toward the first diffractive element; a second diffractive element including two diffraction regions with different diffraction properties that are arranged in a direction corresponding to the tracking direction, each said diffraction region being configured to diffract light that is polarized in a direction that intersects with the particular direction at right angles, the second diffractive element configured to split the write beam that has been reflected from the optical storage medium through each said diffraction region into a transmitted light beam and at least one diffracted light beam; and a photodetector including a plurality of photosensitive elements that are configured to detect the transmitted light beam, the diffracted light beams that have left the two diffraction regions, and the read beam that has been reflected from the optical storage medium.