Research On Imaging Detection And Automatic Parameter Acquisition Algorithm For Laser-Induced Fused Silica Exit Surface Ejection Process

Fused silica is one of the important components of high-power laser devices,and its anti-damage threshold directly limits the power level of the laser.The laser damage process of fused silica mainly includes the formation of micron-sized particle ejection and high-speed shock wave.These processes have the characteristics of high speed,small size and long duration,which cause difficulties in experimental observation.The paper studies the imaging detection of ejected particles and shock waves and the automatic acquisition of kinetic parameters during the fused silica damage process.The main research work and achievements are as follows:1.The design scheme of the dual-frame laser shadow imaging system is proposed.The in-situ double-frame laser shadow imaging system for the exit surface damage of fused silica is built.The double-frame images of the fused silica exit surface ejected particles and shockwave images with high spatial and temporal resolution is obtained.2.The double-frame images registration is realized by the scale-invariant feature transform algorithm.The block-matching and 3D filtering algorithm is used to denoise the particle ejection target area images.Two improved fuzzy C-means clustering algorithms are proposed.By combining gray wolf optimizer and edge constraints,the accuracy of particle recognition is improved.Two particle matching methods based on layered Voronoi diagram and Gabriel graph are proposed.The particle matching of double-frame shadow images is realized,and the dynamic parameters of the ejected particles are calculated.3.The Hessian matrix based enhancement filter algorithm and Bayesian inference algorithm are used to enhance the shock wave characteristics in the image and reduce the coherent noise in the image.The Otsu method is used to process the enhanced shadow images,and the shock wave and the stress wave in images are successfully recognized.The shock wave propagation distance and velocity are obtained.