| 摘要 |
PURPOSE:To detect tracking without being affected by recording bits at the time of recording by separating a laser beam into three beams, i.e. 0-degree light and + or -1-degree light, using the 0-degree light as a laser beam exclusively used for recording or reading, and using either of + or -1-degree light as a laser beam exclusively used for tracking detection. CONSTITUTION:Half width pits 29a, 29b deformed according to tracking detec tion signals f1, f2 of different frequencies, i.e. modulated by tracking detection signals f1, f2 on side walls 28a, 28b are formed at the boundary between side walls 28a, 28b of a recording track 26. After dividing the laser beam into three beams of 0-degree light and + or -1-degree light, the beams are irradiated alongh the recording track. Recording or reproducing is made by the 0-degree light, and at the same time, the level difference between tracking detection signals f1, f2 included in the output signal of a light receiving section that receives reflected light of either of + or -1-degree light is outputted as a tracking error signal.
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