针对短脉冲激光打靶用溅射防护聚合物薄膜做了初步研究。研究了氟化乙丙共聚物(FEP)、全氟烷氧基共聚物和乙烯-四氟乙烯共聚物三种厚度均为25 μm的聚合物薄膜的透过率,结果表明FEP薄膜在355 nm处光透过率达93%,有望用于激光打靶的溅射防护。进一步对FEP聚合物薄膜的波前畸变、激光损伤阈值进行了研究,结果表明80 mm的聚合物薄膜在632.8 nm处的透射波前畸变的峰谷值(PV值)为波长的1.006倍;在采用输出波长355 nm,脉冲宽度9.3 ns的Nd:YAG激光为照射光源波长处,薄膜零损伤概率时的最高激光能量密度为10.35 J/cm2, 100%损伤概率时的最低激光能量密度为11.48 J/cm2。

The debris mitigation is a major challenge for all high-peak-power lasers system. Costly, long lead time focusing parabolas need to be protected from target debris. In order to solve the problem, we employed some preliminary research. In this work, the optical properties of three kinds of thin films (fluorinated ethylene propylene (FEP), perfluoroalkoxy copolymer (PFA) and ethane-tetrafluoroethylene copolymer (ETFE)) were investigated with respect to their application as laser debris shields. The results indicate the transmittance of FEP film at 355 nm is the highest in that of the three films reaching about 93%, though the three thin films all present good transmittance. Thus, the transmittance wavefront and the laser induced damage of FEP film were further investigated. The result indicates that the wavefront error of FEP film is about 1.06 λ. The damage test was performed with a 355 nm neodymium: Yttrium aluminum garnet (Nd:YAG) laser with a 9.3 ns pulse duration, and it is found that the highest non-damage fluence for FEP film is 10.35 J/cm2 and the 100% damage fluence is 11.48 J/cm2.