Research On Removal Methods Of Surface Defects In Fused Quartz Components

The surface quality of the fused quartz component has an important impact on its performance in high-power laser systems.Defects on the surface of the component will not only induce laser damage to the component,but also reduce the quality of laser transmission.Reducing surface defects can help prolong the service life of optical components and improve the stability of laser system operation.Therefore,this article will take fused quartz components as the research object to study the material removal mechanism of CMP,simulate and analyze the relationship between surface defects and laser damage,optimize the composition of the polishing liquid and propose methods for removing the defect.The specific research work is as follows:Analyze the actual morphology and material removal mechanism of the fused quartz element after CMP polishing,and establish material removal model based on contact deformation mode between polishing pad and workpiece.The effect of chemical and mechanical action on CMP material removal was studied by experiments.The results show that the CMP material removal of fused quartz element is mainly realized by abrasive wear.Mechanical action plays a leading role in CMP material removal,and chemical action plays an auxiliary role.The material removal model shows that the material removal rate increases with the increase of the particle size and is proportional to the relative sliding speed.The influence of polishing fluid composition on surface defects was studied by experiments,and the formation mechanism of various surface defects and the mechanism of laser damage induced by defects were analyzed.The results show that there are scratches and pits on the surface of CMP components caused by large abrasive particles,and the larger the abrasive particle size is,the more the number of polished surface defects is.JFC dispersant has better dispersing property,so the surface defects obtained by polishing are the least.The simulation model of the maximum temperature and the electric field modulation of the element is established.The influence of the size,shape,spacing and number of defects on the laser damage is studied by simulation.The results show that the larger the ratio of scratch width to depth is,the smaller the maximum temperature of the element is.And the smaller the scratch distance is,the larger the electric field amplitude is.With the increase of pit size,the maximum temperature and electric field amplitude of the element first increase and then tend to be stable.Compared with the simulation results of defects,the scratch is more likely to cause laser damage.The effects of polishing abrasive,type of surface dispersant and p H value of polishing solution on the surface quality were studied by experiments,and the composition of polishing solution is optimized.50 nm silica abrasive,JFC surface dispersant and p H=11 are the best combination of polishing solution components respectively.In order to reduce the surface defects of components after CMP machining,the removal method of surface defects is proposed,and the quality of machined surface is evaluated from three aspects: surface morphology,surface roughness and surface profile curve.The results show that the surface quality of CMP can be significantly improved by using the optimized polishing fluid or composite abrasive.