| 摘要 |
PROBLEM TO BE SOLVED: To reproduce a high quality magneto-optical signal by providing a first means removing coma aberration caused by transmitting through a polarizing beam splitter, a second means removing astigmatism caused by the first means and a third means causing the astigmatism and stably generating a focus error signal and a tracking error signal. SOLUTION: Luminous flux outgoing from a semiconductor laser 1 irradiates a track 6 on a magneto-optical disk through a planar polarizing beam splitter 2, a collimate lens 3, a mirror 4 and an objective lens 5. Reflected light rotating its plane of polarization transmits through the planar beam splitter 2 to be made incident on a double face concave cylindrical lens 8. The ridgeline of the incident side of the cylindrical lens 8 is parallel to the incident surface of the beam splitter 2, and is orthogonally intersected with an optical axis, and the ridgeline of the outgoing side is tilted by 45 deg. to the incident surface of the beam splitter 2. Thus, the astigmatism and the coma aberration caused at the time of transmitting through the beam splitter 2 are removed. |
