OPTICAL PICK-UP

PROBLEM TO BE SOLVED: To prevent the coming-off of a tracking servo or the like by specifying the direction of a laser diode and the position of a bean shaping prism to reduce the offset of a tracking error signal at the time of using the beam shaping prism. SOLUTION: A laser beam 12 generated from a laser diode 10 is formed into a parallel light beam having nearly elliptic cross section by a collimator lens 14, and it is enlarged in the direction of a minor axis by a beam shaping prism 16 or reduced in the direction of a major axis to shape it into the laser beam 12 having nearly round cross section. It is converged by an objective lens 24 and formed into a nearly round beam spot 38 on the track of an optical disk 18. The direction of the laser diode 10 is set and the beam shaping prism 16 is disposed so that the direction of shaping the laser beam 12 by the beam shaping prism 16 appears in the direction along a track 40 on the surface of an optical disk 18.