Design Of Absorber And Study On The Effects Of Optical Element Defects And Laser Interaction

Due to the complexity of high-energy laser systems,the scattering and residual reflection of optical components can cause the convergence of light,producing highenergy stray light.High-energy stray light has become a "bottleneck" problem in the development of ICF(Inertial Confinement Fusion)technology.Stray light in high-energy laser systems is primarily handled by the absorption of specific types of absorbing glass.However,while absorbing glass absorbs high-energy stray light,it generates a large amount of damaged particles and contaminates the high-energy laser system.How to solve the stray light problem while avoiding damage to the particle pollution laser system becomes the key to the further development of ICF.In this thesis,different types of absorbing glass are selected as the light absorbing materials for the wavelength and energy density of stray light.Due to the high absorption and low transmission optical properties of the absorbing glass,it is easy to generate damaged particles by laser irradiation.Therefore,in order to ensure that the damaged particles do not pollute the high-energy laser system,a composite structure of fused silica and absorbing glass is used to absorb stray light.In order to improve the application range of the absorber,it is necessary to study the effects of the absorbing glass and fused silica and the laser.The effects of the defects of fused silica and absorbing glass on the laser damage ability are analyzed by simulation and verified by experiments.The scope of application of the absorber provides a basis.Firstly,according to the characteristics of stray light,select the appropriate absorption glass and fused silica,calculate and test the reflectivity and transmittance of fused silica and absorbing glass at normal incidence and oblique incidence,and adopt a composite V-shaped structure with multiple reflection absorption.A light transmission model was established,and the simulation obtained the light intensity at different positions to verify the structural design.Secondly,the type of scratch defects on the surface of the absorbing glass is analyzed,and the finite element simulation model of the interaction between laser and matter is established.The ideal surface of the pulsed laser,radial scratches,Hertz scratches and trailing scratches are simulated.Field and stress field directions were used to study the effects of different shapes and different parameters on the damage ability,and the effects of different scratches on temperature and stress distribution were investigated.Then,the effect of bubble defects on the light field modulation is established for the bubble defects existing in fused silica.The influence of bubble defects on the light field modulation is analyzed.The effects of bubble defects with different shapes and different parameters are discussed respectively.Finally,laser damage was used to study the damage of absorbing glass and fused silica.The scratches of different parameters were established.The influence of scratches on the damage was studied from the number of particles generated by the damage.The simulation was verified.The bubble defects of different paramet ers were calibrated by microscope,and the laser irradiation was performed by n-on-1 method,and the damage threshold was measured respectively,and the influence of bubble defects was analyzed.