Research And Development Of LD-Pumped Solid-State Laser Control System

Laser-diode (LD) pumped solid-state laser (DPL) is widely used for its advantages of small volume, high efficiency, good beam quality, and long longevity. DPL control system is the necessary equipment for DPL normally working. Its performance has large influence on the DPL's characteristics such as the conversion efficiency and beam quality. It is a key technology for the DPL system to be on the way to the practicality and integration, and nowadays it has become one of the research and development hotspots.On the basis of analyzing the characteristic of LD power supply and thermal effect of DPL,a new type of DPL control system is designed in this thesis. It contains two parts, i.e., LD power source and DPL temperature controller. A closed loop temperature control system is designed, it uses a high performance microprocessor of ADuC848 as a control core, a thermistor with negative temperature coefficient as a temperature sensor, a thermoelectric cooler (TEC) as a heating and cooling component, and a digital PID as the control algorithm. A constant current power supply for the LD is composed of the protecting circuits and the voltage-controlled current source, which is under the control of the output voltage from a digital-analog convertor. The main contents of the thesis are as follows:Firstly, the configuration, advantages and development prospect of the DPL systems are introduced. The characteristic such as conversion efficiency and beam quality influenced by the DPL control system is analyzed, and the present status of the DPL control systems is summarized.Secondly, the LD-used constant current power supply is designed. The experimental results has shown that the current, which output from the power supply with a current stability of smaller than 0.1%, can be adjusted in a range from zero to five amperes.Thirdly, on the basis of analyzing the thermal effects of LD and DPL system, a design scheme of DPL temperature control system is proposed. The system hardware design is fulfilled. The design methods, circuit diagrams of the temperature measurement circuits, the TEC drivingcircuits, and serial communication circuits are all provided.Fourthly, the theory and design method of digital PID algorithm is studied, and the mathematic model of the control object is established.Fifthly, the system software is designed. The flow chart of main program module is offered.Lastly, the effect of temperature control system is examined experimentally. The results indicate that the temperature can be controlled in a range from 10℃to 40℃with a stability of 0.1℃.The DPL control system researched and developed in this thesis can meet the design requirements, and has the advantages of simple circuit, reliable working. It has higher reference value for the research and applications of DPL system.Keywords: Laser-diode; solid-state lasers; current source; temperature control; digital PID...