| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head apparatus and an optical information recording and reproducing apparatus which enable a focusing error signal and a tracking error signal to have no offsets and which detect the deviation of the substrate thickness and the radial tilt of an optical recording medium. SOLUTION: A diffractive optical element 3a divides light emitted from a semiconductor laser 1 into a main beam, a first sub beam, and a second sub beam. The first sub beam has the same intensity distribution as that of the main beam, and the second sub beam has intensity distribution different from that of the main beam. The sum of the focusing error signal of the main beam and the focusing error signal of the first sub beam, and the difference between the tracking error signal of the main beam and the tracking error signal of the first sub beam are treated as a final focusing error signal and a final tracking error signal, respectively. The deviation of the substrate thickness and the radial tilt of a disk 7 are detected based on the deviation between the zero crossing point of the focusing error signal of the main beam and the zero crossing point of the focusing error signal of the second sub beam and of the tracking error signal, respectively. |
