| 摘要 |
PURPOSE:To stabilize a light output of a semiconductor laser at the time of generating high power for recording information by providing a means for emitting the semiconductor laser with reference to a reference value only when an information recording signal is at a high level after setting a focusing state. CONSTITUTION:An output of the semiconductor laser is calibrated under a nonfocusing state prior to closing an autofocus control loop to be stored, and when the information recording signal is at the high level. a power control is performed based on this storage signal. A signal of a moudulation circuit 13 is also sent to a 2nd switch circuit 14, and a reference voltage of a storage circuit 10 at the time of the high level or a voltage from a 1st switch circuit 9 at the time of a low level is selected to be sent to a differential circuit 4. That is, when the recording information signal is at the low level, a power control is performed in real time after multiplexing high frequencies, and power control is carried out with a value set before recording, and hence even when there is return light at the time of focusing, the recording can be performed by keeping properly the power of the semiconductor laser. |
