Patent ID: 7092347

Claim:
An optical pickup apparatus comprising: a light source which emits a light beam; a holographic optical element which: splits the emitted light beam into first and second light beams, polarizes the first light beam in a first direction, polarizes the second light beam in a second direction and generates a predetermined spherical aberration to the second light beam; an objective lens which focuses the first and second light beams to concurrently form a main light spot, having no aberration, and an auxiliary light spot having the predetermined spherical aberration, on an optical disk; first and second photodetectors which photoelectrically convert light beams reflected from the optical disk and corresponding to the main light spot and the auxiliary light spot into first and second signals; and a signal processor, which delays a phase of the second signal to synchronize the first signal and the second signal and combines the first and second signals to output a reproduction signal which corrects for a deviation in a thickness of the optical disk.