离子辅助沉积大口径传输反射镜面形控制研究

 针对大型激光系统中光束质量低和波前畸变等特点，采用离子辅助电子束蒸发技术成功实现对多层膜残余应力的精确控制。通过分析氧化铪、氧化硅单层膜残余应力变化规律，研究了离子源束压、束流参量对膜层折射率、残余应力性质及大小的影响。540 mm×340 mm×60 mm规格大口径传输反射镜面形PV值达到0.5λ(λ=632 nm)，小光束损伤测试情况下，样品元件的损伤阈值大于30 J/cm2(N-on-1,1 064 nm,5 ns)，利用该技术制备的大口径传输反射镜已获得成功应用。

Surface shape control for large ion assisted deposition mirror

To improve wavefront quality in large scale laser, the residual stress in multi-layer films was controlled precisely by ion-assisted e-beam evaporation. Based on the analysis of the residual stress variation in single HfO2 layer and SiO2 layer, the effects of ion-source beam voltage and beam current on refractive index and residual stress in films were studied. The PV value of 540 mm×340 mm×60 mm reflective mirror was controlled below 0.5λ (λ=632 nm). The damage threshold of the specimen tested with small-size beam was higher than 30 J/cm2 (N-on-1,1 064 nm, 5 ns). The large-size reflective mirror manufactured with this technology is applied successfully in a large aperture prototype device.