| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain high accuracy of focus pull-in control with respect to a multilayered information recording layer of an optical disk. <P>SOLUTION: A focus pull-in parameter is generated in each information recording layer based on a focus error signal (FE) through steps of: subjecting the optical system of an objective lens (13) to spherical aberration correction adapted to a target information recording layer; holding the intensity of a focus error signal and the number of times of focus errors, which sequentially vary when the objective lens is moved closer to the optical disk (10) while irradiating the disk with a beam; and generating a determination threshold of the focus error signal and a determination number of times of focus errors based on the determination threshold, by using the held information, as focus pull-in parameters of the information recording layer. Focus pull-in control is carried out to the target information recording layer by using the generated focus pull-in parameters. <P>COPYRIGHT: (C)2012,JPO&INPIT |
