| 摘要 |
PURPOSE:To detect any abnormal deterioration or/and abnormal high laser output by a simple circuit enabling any trouble of a laser diode, etc. to be prevented by a method wherein a judging means to make a judgment on the deterioration of a semiconductor laser or/and the abnormality of a semiconductor laser output making reference to the fluctuation of monitor output is provided. CONSTITUTION:The title semiconductor laser device is composed of a laser diode 1, a detecting circuit 2 detecting the monitor current of laser output from the laser diode 1 to output monitor voltage V0, an APC circuit 3 comparing the monitor voltage V0 with a reference voltage V1 to keep the laser output from the laser diode 1 constant and a judging circuit 4 comparing the monitor voltage V0 with another reference voltage V2 to make a judgment on the deterioration of the laser diode 1 or the abnormality of laser output. When the deterioration of the laser diode 1 advances, the driving current to assure a specific laser output increases, however, the output current from an operating amplifier is bypassed to a Zener diode 18 to prevent an overcurrent from running into the laser diode 1. |
