Design And Implementation Of Temperature Control System For Arf Excimer Laser

ArF excimer laser is widely used in scientific research,medical and industrial fields.Laser properties are closely related to temperature of the discharge chamber.In order to achieve high precision and high stability of temperature control,this paper focuses on the structure and algorithm of temperature control system and designs a temperature control system.The main research work and conclusions of this paper are as follows:According to ArF excimer laser's application,the demand of temperature control system is put forward.Three temperature control schemes are designed.Advantages and disadvantages of three schemes are compared from four aspects of control accuracy,economy,integration and human-computer interaction.Finally,the scheme of controlling flow rate by proportional valve controlled by industrial computer is adopted to realize the requirement of temperature control.The temperature control system is designed in detail from three aspects of mechanical structure,electricity and software.The three-dimensional model of water distribution unit is built.The electrical schematic diagram is designed,and the temperature control software is compiled.Because of the fluctuation of pressure in water supply system,it is necessary to restrain the interference of pressure fluctuation on temperature control accuracy.Based on single-loop PID control,cascade PID control is designed.It is proved theoretically that cascade control has stronger anti-interference ability than single loop control when pressure of water fluctuates.Three incremental PID controllers of single loop temperature control PID,main PID and vice PID in cascade control are designed.The transfer function of the proportional valve is identified to adjust Parameters of the flow control PID,and the flow control simulation is carried out in Simulink.Two anti-integral saturation methods of integral separation and amplitude limitation are designed to avoid the problem of integral saturation in flow control.Finally,the temperature control experimental platform is built to verify the accuracy and stability of the temperature control system.Flow control experiments show that the flow control meets the accuracy requirement of +0.1L/min.Temperature control experiments show that the temperature control system can meet the demand target of 45±0.1?.The comparison between single loop PID temperature control and cascade PID temperature control shows that cascade control has stronger anti-interference ability than single loop control when pressure of water fluctuates.