运用溶胶改性和溶剂置换的方法制备以癸烷为溶剂的SiO₂溶胶,通过单面旋涂方法在方形50 mm×50 mm×10 mm 的KDP晶体基片上制备均匀性良好的膜层。使用分光光度计测试涂膜的晶体基片,涂制三倍频及基频二倍频减反膜的KDP晶体基片在378 nm和835 nm处的透过率峰值均大于99.5%,膜层减反射效果良好。结合过滤技术及超声波清洗技术实现了膜层制备过程中的缺陷控制,将经过缺陷控制的三倍频减反膜涂制在洁净度高的熔石英陪涂片上,并在测试前进行激光(波长为355 nm,脉宽为3 ns)预处理,得到的三倍频减反膜的抗激光损伤阈值为(14.0±2.1) J·cm ^-2。

In this study, silica sol with decane as a solvent was prepared by the sol modification and solvent replacement method. A film with good uniformity was coated on 50 mm×50 mm×10 mm square KDP crystals using the single spin coating method. The optical properties of the film coated on the KDP crystals were tested using a spectrophotometer. The peak transmittance value of the KDP crystal substrate coated with the third harmonic frequency and the fundamental frequency of the second harmonic frequency antireflective films could achieve more than 99.5% at 378 nm and 835 nm, respectively. The defect control in the preparation process of the coating film was realized by the combination of the filtration and the ultrasonic cleaning technology. The third harmonic frequency antireflective film with defect control was coated on a high-cleanliness fused silica substrate and pretreated by laser conditioning before testing. The laser-induced damage threshold of the third harmonic frequency antireflective film reached (14.0 ± 2.1) J·cm -2 measured by a laser with 355 nm wavelength and 3 ns pulse width.