| 摘要 |
PROBLEM TO BE SOLVED: To minimize modulation by a groove/land or a pit train related to a focusing error signal and to attain the realization of a stable focusing servo operation. SOLUTION: This optical pickup is constituted so as to obtain focusing error information by an astigmatism method. The arrangement condition of an objective lens 5 is set so that the direction DOB of astigmatism generated by the objective lens 5 becomes a direction within a prescribed range to the direction DSD of the astigmatism generated by an astigmatism generating element (cylindrical lens 7). The prescribed range is made to an angular range of ±50 deg.C for the direction DSD of the astigmatism. |
