An optical pickup capable of focusing a main light spot and an auxiliary
light spot including optical aberration when an optical disk is not
tilted, and analyzing the main light spot and the auxiliary light spot
with a photodetector, thereby correcting aberration. The optical pickup
includes a light source emitting light; light splitting means for
splitting an incident beam into at least two light beams including a first
beam and a second beam so as to form at least two light spots on an
optical disk; optical path changing means for changing the traveling path
of the incident first and second beams; an objective lens focusing the
first and second beams to form a main light spot and an auxiliary light
spot, respectively, on the optical disk; a photodetector having first and
second light receiving portions receiving the first and second beams
reflecting from the optical disk and passing through the optical path
changing means, respectively, and performing photoelectric conversion on
the received beams to produce and detect electrical signals; and a signal
processor correcting aberration caused by tilting of the optical disk,
using the electrical signals.
