| 摘要 |
PURPOSE:To condense plural optical beams on a recording track accurately and stably with one condenser lens by providing a tracking error detector and a tracking controller for each of plural optical beams. CONSTITUTION:The light having 830nm wavelength from a light source 1 and the light having 780nm wavelength from a light source 2 are irradiated to a recording medium with one condenser lens 10. In this case, the reflected light of the first optical beam is made incident on a photodetector 13 to detect the tracking error, and a lens actuator 11 is driven through a control circuit 15. Meanwhile, the reflected light of the second optical beam is made incident on a photodetector 14 to detect the tracking error, and a galvano-mirror 7 is driven through a control circuit 16. Thus, plural optical beams are condensed on the recording track accurately and stably with one lens 10.
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