| 摘要 |
PURPOSE:To detect the deterioration of the characteristics of a laser, and to alarm the lifetime of the laser before the laser gets trouble by a method wherein a current detector, a temperature detector and a photodetector are provided, one parameter from among three parameters namely, temperature, driving current-optical output is kept constant, while other two parameters are compared with each other and the deterioration of the laser is detected. CONSTITUTION:The I/O characteristics of a nonlinear type amplifier 5 are determined previously so that the relationship between output voltage and a temperature in case of a normal laser coincides with the relationship between the output voltage and temperature of the nonlinear amplifier 5. A current detector 2a detecting the driving currents of the laser 1a, a temperature detector 3 detecting the temperature of the substantial laser 1a a photodetector such as a photodiode 1b detecting a laser beam output are set up, and a comparator 6 comparing the laser beam output and an optical output in the predetermined laser driving currents of the normal laser at a temperature at that time to prescribed laser driving currents is fitted, thus accurately detecting the deterioration of the laser 1a quickly, thereby alarming the lifetime of the laser before the laser 1a gets trouble. |
