Study On Key Techniques Of Medical And Industrial Excimer Laser System

As a powerful UV light source,excimer laser of discharge excitation are widely used in industrial and medical fields with high-peak power,short-wavelength,high-photon energy,etc.In medical and industrial application,research and development of high stability practical product of excimer laser is an important direction,but there are many factors that can influence the stability of laser products,such as stability and precision of energy storage capacitor charging power supply(CCPS)of laser,electromagnetic compatibility and feedback closed-loop stability control for the whole machine,and so on.In order to further improve the overall performance of the excimer laser products and promote its practical application this paper studies the determinants above in detail.First of all,the author of this paper review the development history and application field of excimer,and summarize the key technology of electric excitation excimer laser including low-frequency large-energy technology,high-frequency technology,gas compensation technology and so on.Meanwhile,this paper also introduces the main topology and related technologies of energy storage capacitor charging power supply of excimer laser and expounds the electromagnetic compatibility of excimer laser system,and emphasis the research significance and the content of this paper.In order to meet requirements of the energy storage capacitor charging of excimer laser in industrial and medical,the author carry out research for high frequency and low frequency capacitor charging power supply respectively.High repetition frequency capacitor charging power supply based on capacitor and inductor(LC)series resonant topology achieve high-precision charging by introducing auxiliary circuit and the sequential control system.Under the condition of 5.44?F energy storage capacitor,the pulse system get the performance of maximum voltage 1.92 kV,accuracy of the output voltage<0.05%,repetition rate 4 kHz,energy transfer rate 4 kJ/s.Low frequency capacitor charging power supply adopts the push-pull topology combined with active low-loss absorption circuit achieve linear charging for storage capacitance.Its output voltage is from 10 kV to 35 kV and the switching frequency is 45 kHz.The average charging power is 2.6 kJ/s and the charging accuracy is 0.1%.Finally,KrF excimer laser with a 64 nF energy storage capacity can gain maximum 820 mJ output energy using this capacitor charging power supply.The two kinds of power above meet the practical requirements of charging precision and performance.Since electromagnetic compatibility is an important indicator which need to be tested before excimer laser products into the market and must meet the national standards,the fourth chapter of this paper have researched this indicator.Electromagnetic radiation characteristics of excimer laser is analyzed from the angle of the experiment and overall design is implemented combined the shielding theory and electromagnetic compatibility.The experimental results show that the shielding effectiveness of the shielding is more than 40 dB and the machine can be reliable and stable operation.In order to further improve the output energy stability of excimer laser,the paper carry out the theoretical research and experimental verification in the end.The laser energy attenuation model and proportional integral(PI)algorithm based on energy compensation by the excitation voltage is established,which is carried on the theoretical analysis and simulation.Based on the design of the low frequency capacitor charging power supply,308 nm excimer laser skin therapeutic apparatus is constructed and the rationality of the PI algorithm is verified.The results show that the excimer laser output energy can still maintain a target within 17.5 mJ and energy variance is slowly rising from 0.2%to 3%in the one hundred thousand pulses after introducing the proportional integral algorithm,which well meets the usage requirements of excimer laser skin therapeutic apparatus.