Study On Mechanical Lapping And Polishing Process Of Yttrium Aluminum Garnet Crystal

Yttrium aluminum garnet?YAG?is the most commonly substrate material used in the field of laser crystal.Through doped with rare earth ions,YAG crystal can be used in the direction of laser weapon,processing and measuring.With the continuous development of laser technology,people have put higher requirements on the surface quality and surface shape precision of laser crystal.It is difficult to guarantee the surface roughness and surface flatness at the same time.This paper developed a set of process scheme,aiming to concerted control YAG crystal surface quality and shape accuracy method,and the main contents are as follows:?1?The mechanical polishing of YAG crystal has been studied,adopting B₄C?W7?during coarse lapping.During the precision lapping,the Al₂O₃?W2.5?has been used.Through experiment of the rotational speed of disk,lapping pressure and the concentration of particle,choosing the best lapping technology.The flatness of YAG can reach 476 nm.?2?Studying the type of polishing disk how to influence the surface defects of YAG crystal,and the synthetic copper disk is used during coarse polishing.Analyzing the abrasive agglomeration how to influence the surface defects of YAG crystal,and add SDBS,PVP and CTAB into the solution.From the aspect of macroscopic observation,Zeta potential,absorbency and particle size,it is shown that 0.5%?wt?SDBS can effectively prevent the agglomeration of abrasives.Polishing with the new developed specialized polishing liquid,the surface defects of YAG crystal has been significantly decreased.?3?Studying the mechanical polishing of YAG crystal,the synthetic copper disk has beed used during the coarse polishing.The abrasive is Al₂O₃?W0.3?,after the single factor experiments of rotational speed,lapping press and the Ra value 3.0 nm and the flatness 86 nm can be obtained after polishing 45 minutes.The deformation of polishing pad is analyzed by finite element method and the IC1000/Suba IV has been used during precison polishing and the abrasive is Al₂O₃?W0.05?.The Ra value 0.7 nm and the flatness 100 nm can be obtained after polishing 30 minutes,which meets die expectation.