| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately and stably compensate a spherical aberration for an unrecorded write-once disk, and to detect a spherical aberration error signal with simple part composition in real time. <P>SOLUTION: For an unrecorded write-once disk 20, a tracking servo is made inoperative, a push-pull signal is detected by a push-pull signal generating circuit 34 from outputs of a photo detector 12, in an in-focus state and an out-of-focus state, and a spherical aberration error signal A is obtained by a spherical aberration error detecting circuit 31 by calculating a difference in amplitudes between these push-pull signals. After compensating the spherical aberration with the signal A, a specific pattern signal is recorded in an area for trial writing and is reproduced in the in-focus and out-of-focus states. An amplitude of the reproduced signal for each state is obtained by a reproduced signal generating circuit 32, and a spherical aberration error signal B is obtained by the spherical aberration error detecting circuit 31 by calculating a difference between these amplitudes. The spherical aberration is compensated with the signal B. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
