Study Of Key Technology Of Ld Laser Cooling System

As the development of the laser technology, laser is extensively applied in industy, medical treatments, national defense etc. Because of the high quality of output beam, high efficiency, long life, laser diode (LD) has become an important type of solid-state lasers. However, the heat generated by LD itself greatly influences the characteristies of LD, such as the wavelength, output power, and also influences the accuracy and life time. Therefore, it is needed to strict control of changes of the temperature of LD.This research focuses on the temperature of the small and medium-power LD. AT89S52 chip is used as the core control device. Digital temperature sensor is used to detect temperature of LD. The thermoelectric cooler(TEC) is used as temperature control conduct. And a control algorithm of combining the fuzzy theory with PID parameters self-turing is adopted in the system.This thesis mainly includes seveal parts as follows: First, the influence of temperature on output characterisic of LD is mainly described. And the situation of the temperature control of LD at home and abroad is described. The temperature control based on Fuzzy- PID control scheme is proposed, and its feasibility is analyzed. Second, the Fuzzy-PID controller is designed based on the Fuzzy-PID control theory. The design process is as follows: Above all, the method of critical proportional band is used to get the initial value of parameters of PID. Then the temperature deviation and its change rate of LD are input to the controller, the three parameters of digital PID, which are proportional coefficient, integral and ifferential time, are modified real-time according to the fuzzy elationship.Third, the hardware and software are designed. Forth, the LD temperature control system has been established.The experimentally obtained results indicate that within the temperature rnage of 10℃to 40℃, the resolution of the temperature measuerment is better than 0.1℃,and the stability of temperature control system is better than 0.2℃,and the establishing time is about 3 minutes. This temperatuer conortl sysetm provides a good temperature control solution for the small or middle power LD temperature control.