Design Of Power Monitor System For High Power Axial-flow CO₂ Laser

The stability and accuracy of laser power directly influence the quality of laser processing. During the course of laser processing, monitoring the variation of laser power and improving its stability and accuracy in real-time are very important for increasing the pass rate of products.Therefore, a real-time online laser power monitor system is developed for high power fast-axial-flow CO₂ laser, and design ideas and methods of the system are all illustrated in this thesis. The C8051F series microprocessor and Fuzzy control system are used as the control center of the system, and the sampling signal from the infrared detector is used as the feedback of the laser power monitor system for close-loop control.In this thesis, the trend of the CO₂ laser and the structure of the fast-axial-flow CO₂ laser are introduced at first. Then, according to the characteristics of the fast-axial-flow CO₂ laser, the design method of hardware and software of the laser power monitor system is proposed; the structure and the working principles of the power monitor system are also introduced later. The C8051Fxxx microprocessor is the center of the circuit. The control circuit of sampling and processing of the power signal is well designed. In signal sampling circuit, traditional mechanical potentiometer is replaced by digital potentiometer, so the signal amplification can be intelligent regulated. Because of the complexity of the circuit, a power management circuit is designed for the management of the power supply of entire system. At the same time, the microprocessor interface circuits'design has also been introduced in detail. The control voltage signal of the power is adjusted through the PID regulator, and closed loop control is achieved through automatic adjustment of the discharge current which can ensure the stability of the output of laser power. Interface circuit control program of C8051Fxxx and serial communication program are also designed, so that the whole system can be operated through the microcontroller or PC control. The programs designed for the system are all successfully compiled through Keil C compiler. Finally, the important points of this article are summarized at the end of this thesis.