| 摘要 |
PURPOSE:To eliminate pit variations in shape and diameter at the time of recording with a semiconductor laser and to improve the S/N by providing a 2nd control circuit and controlling pulse power that is added at the recording time to be constant. CONSTITUTION:A semiconductor laser driving current is controlled by a reproducing APC (automatic output power control) circuit 106' as a 1st control circuit to make a DC power component out of the output power issued from the semiconductor laser 100 to be the DC power at the reproducing time even at the time of recording. A recording APC circuit 108 as the 2nd control circuit is operated at the time of recording, so that a pulse current driving circuit 107 is controlled to make the pulse power to be added at the recording time of the semiconductor laser 100 constant. Consequently, the stable light emitting output power can be obtained at the time of both recording and reproducing without being influenced by return light. By this method, no variations take place from the pit shape and pit diameter especially at the time of recording, and the S/N is improved accordingly. |
