| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for detecting a tracking error signal by using push-pull signals of a main beam and a sub-beam, which cancels the offset caused by an objective lens shift and disk tilt at a low cost. <P>SOLUTION: The laser beam emitted from a semiconductor laser 1 is converted to parallel beams by a collimator lens 2 and is divided into a main beam 30, a sub-beam (+1st<SP></SP>order light) 31, and a sub-beam (-1st order light) 32 by a tilt multidivision type phase difference grating 3. The beams are passed through a beam splitter 4 and is then condensed on the track 61 of an optical disk 6 by an objective lens 5. Light is reflected through the objective lens 5 by the beam splitter 4 and is guided to photodetectors 8 (8A, 8B and 8C) by a condenser lens 7. <P>COPYRIGHT: (C)2004,JPO |
