Laser Multi-pass Amplification System Stray Light Analysis

After signing Comprehensive Nuclear-test-ban treaty (CTBT),Laser fusion,as the best.technological way of controlled fusion,got the big countries' great attention. The multi-pass amplification of laser is widely used in high power Laser system as the driver of nuclear fusion,for it can improve system efficiency effectively and reduce manufacturing cost. Stray light generated in multi-pass amplification forms a lot of ghost images,which not only seriously influence the Laser beam quality and propagation properties,but also damage the optical component.Taking stray light in "Shenguang III" as the study subject and basing on the basic principle of geometrical optics,Applying the technological path of paraxial ray and real ray tracing,a new analytic way and data structure,which suits for the specific requirement in analysis and process of ghost images,is presented. With the sample of the beam in high power multi-pass amplification,the three-dimensional mathematic model had been set up and the calculation method which functions well in solving these mathematic model is got,the computer simulation of the optical path is also realized. The analytical software can Comprehensively detect these ghost images generated by ghost reflections and simulate the energy attenuation process of ghost beam. The position of ghost image can be picked out,the potential hazard of ghost images to key elements can be verified,and the irradiance at ghost image and key elements can be described.The software meet the need of analysis and calculation of ghost images in multi-pass amplification,its analytic result direct apply the optical design of Laser multi-pass amplification. It can reduce the time and cost of optical design and have actual significance.