The Design And Research Of High-Precision Temperature Control System Of Excimer Laser

At present, excimer laser has been widely used in scientific research, micromachining, medical fields etc. When the excimer laser is working, its discharge chamber generates large volume of heat, which can cause the temperature of the chamber too high and further affect the energy stability of laser and other working parameters. So it is necessary to control the temperature of excimer laser to ensure the laser run in the best temperatures state. For example, preferred operating temperatures of a KrF excimer laser is in the range of about 50℃ and preferred operating temperatures of an ArF excimer laser is in the range of about 60℃.The research object is the chamber temperature of ArF Excimer laser in this paper. Platinum resistance temperature detectors Pt100 are used to sample the temperature and proportional valve produced by Burket Company, Germany is used as the actuator. A temperature control system was designed which take the MC9S12XS128 as main controller. The system designed has the properties of small volume, many interface, high temperature control precision and is easily to debug. The system is composed of three parts: temperature sampling module, controller, water-cooling structure. Firstly, a review on temperature measurement and control was introduced, then the system control method was given and the hardware and software for the system were researched and designed. Among them, incremental PID algorithm, improved incremental PID control algorithm and intelligent PID control system were mainly discussed. By simulation and experiment, temperature control effects under the three algorithms were compared. The results showed that all three algorithms realized temperature control with the temperatures were controlled within ±0.2℃; under the intelligent PID control algorithm, the system’s adjusting time was shorter and overshoot was smallest and the system could keep good stability in a long term when the working frequency was changed. Finally, by observing the experiment result, a big delay exists in the system was found. So smith predictive control was researched, theoretical simulation results show that the system’s stability and dynamic performance can effectively improved.