| 摘要 |
PURPOSE:To enable an optimum light-intensity beam to be maintained even if temperature changes by detecting temperature or temperature change of a semiconductor laser from change in drive current when performing automatic output adjustment of the semiconductor laser and then changing a set value of drive current when performing constant current drive according to change in detection signal. CONSTITUTION:A monitor photo diode 9 is provided within a semiconductor laser 1 and then an output of the diode 9 is sent to an automatic output adjustment (APC) circuit 10. The circuit 10 performs feedback control of drive current of the laser 1 according to an output of the diode 9 and maintains an output of the laser 1 to be constant but drive current changes according to temperature change of the laser 1. A controller 7 reads change in the drive current from a semiconductor drive circuit 5 and then detects temperatur change of the laser 1 based on a specified relationship between the drive current and temperature. Then, when the circuit 10 stops APC operation and switches to a constant current drive at the time of recording, a setting value of an optimum drive current is output to the circuit 5 based on a specified relationship between the drive current and temperature of the laser 1, thus enabling an optical beam to be at an optimum intensity constantly. |
