Potential damage threats to downstream optics caused by Gaussian mitigation pits on rear KDP surface  

作　　者：Hao Yang Jian Cheng Zhichao Liu Qi Liu Linjie Zhao Chao Tan Jian Wang Mingjun Chen 

机构地区：[1]State Key Laboratory of Robotics and System,Harbin Institute of Technology,Harbin 150001,China [2]Research Center of Laser Fusion,China Academy of Engineering Physics,Mianyang 621900,China

出　　处：《High Power Laser Science and Engineering》2020年第4期59-67,共9页高功率激光科学与工程（英文版）

基　　金：supported by the Science Challenge Project(No.TZ2016006-0503-01);National Natural Science Foundation of China(Nos.51775147 and 51705105);Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001);China Postdoctoral Science Foundation(Nos.2017M621260 and 2018T110288);Heilongjiang Postdoctoral Fund(No.LBH-Z17090);Self-Planned Task Foundation of State Key Laboratory of Robotics and System(HIT)of China(Nos.SKLRS201718A and SKLRS201803B)。

摘　　要：To determine whether a potassium dihydrogen phosphate(KDP)surface mitigated by micro-milling would potentially threaten downstream optics,we calculated the light-field modulation based on angular spectrum diffraction theory,and performed a laser damage test on downstream fused silica.The results showed that the downstream light intensification caused by a Gaussian mitigation pit of 800μm width and 10μm depth reached a peak value near the KDP rear surface,decreased sharply afterward,and eventually kept stable with the increase in downstream distance.The solved peak value of light intensification exceeded 6 in a range 8–19 mm downstream from the KDP rear surface,which is the most dangerous for downstream optics.Laser damage sites were then induced on the fused silica surface in subsequent laser damage tests.When the distance downstream was greater than 44 mm with a downstream light intensification of less than 3,there were no potential damage threats to downstream optics.The study proves that a mitigated KDP surface can cause laser damage to downstream optical components,to which attention should be paid in an actual application.Through this work,we find that the current manufacturing process and the mitigation index still need to be improved.The research methods and calculation models are also of great reference significance for related studies like optics mitigation and laser damage.

关 键 词：downstream threats KDP laser damage MICRO-MILLING MITIGATION 

分 类 号：TQ131.13[化学工程—无机化工]