| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a stable servo signal in the case of recording information in a multilayer disk without forming a guide groove in all recording layers in advance in the multilayer disk. <P>SOLUTION: A diffraction grating 11 branches a light beam radiated from a semiconductor laser 50 into a main beam and first and second sub-beams, and an objective lens 2 irradiates the beams to a recording layer of an optical disk to form at least three spots. The spots 20d, 20e of the first and second sub-beams are located in a recorded area of the recording layer, a photodetector 10 detects the reflection beams thereof, and a differential signal of a sub-push-pull signal is subjected to tracking control as a tracking error signal. On the other hand, at the spot 20a of the main beam, information is recorded in an unrecorded area of the recording layer. <P>COPYRIGHT: (C)2013,JPO&INPIT |
