Analysis And Design Of Signal Detection Circuit Of RF Excited CO₂ Laser

RF excited CO₂ laser has the advantages of high power output, good beam quality, high electro-light conversion efficiency and compact structure. The wavelength is suitable for transmission in the air. So, the laser is extensively used in industrial laser processing field.RF excited CO₂ laser can't operate stably for a long time unless precise detecting and controlling of its important parameters have been carried out. The thesis aims to analyze and design the signal detection system of the measurement and control system of the laser, realize the intelligent detection of the signals of the laser precisely and stably, and ensure the stable operation with high efficiency.The main research achievements are shown as follow:(1) The operation principle and structure of the laser have been analyzed, and the measurement and control system of the laser has been designed on this basis.(2) The thermal deformation of the lens for the high power laser beam and the influence of the deformation on the beam quality have been analyzed in theories and experiments. Considering the characteristic of so many temperature parameters, the scheme of temperature detection of many points has been adopted. The temperature sensor NTC and the thermal compensation device PTC have been described in detail for the choice of sensors. The temperature detection circuit and the lens heating circuit have been designed reasonably.(3) In view of the difficulty of direct detection, the signals have been detected indirectly by using the equivalent matching network algorithm. The scheme of observing the laser working state by the U-I curve has been put forward. The probe has been described in detail for the choice of sensors. The U/I detection circuit has been designed reasonably.(4) To realize the procedure control and the self-locking and inter-locking protection effectively, the switch signals have been analyzed comprehensively, and the detection principle of every switch signal has also been analyzed. Then the scheme of detecting has been put forward. The measurement system has the advantages of comprehensive signals, high stability and good real-time performance. With the powerful calculating ability, the system can display abundant information which ensures the operation of the laser safety.