球面元件表面AlF3薄膜的光学特性和微观结构表征

在模拟球面元件曲率半径的仿面形夹具上镀制了AlF3单层薄膜，并对不同口径位置上的薄膜进行了比较，以表征球面元件表面镀制薄膜的光学特性和微观结构。首先，采用紫外可见光分光光度计测量了不同口径位置上薄膜样品的透射和反射光谱，反演得出AlF3的折射率和消光系数。然后，使用原子力显微镜观察了样品的表面形貌和表面粗糙度。最后，使用X射线衍射仪对薄膜的内部结构进行了表征。实验结果表明：在球面不同位置镀制的AlF3单层薄膜样品的光学损耗随着所在位置口径的增大而增大。口径为280 mm处的消光系数是中心位置处消光系数的1.8倍，表面粗糙度是中心位置的17.7倍。因此，球面元件需要考虑由蒸汽入射角不同带来的光学损耗的差异。

Characterization of optical and microstructural properties of AlF3 thin films deposited on spherical element

Single AlF3 layers were deposited upon fused-silica substrates placed on a simulated fixture which has the same radius of curvature with the spherical element to characterize the optical and microstructural prop -erties of the AlF3 films.First, transmittance and reflectance spectra of AlF 3 layers at different positions on the fixture were measured by an UV-visible spectrophotometer from 185 nm to 800 nm, and their refractive indexes and extinction coefficients were obtained .Then the surface morphologies and surface roughnesses of AlF 3 lay-ers were assessed with an Atomic Force Microscopy （AFM）.Finally, the X-ray Diffraction（XRD） was used to characterize the microstructure of AlF 3 layers.Experimental results indicate that for AlF 3 layers deposited at different diameters on the spherical element , their optical losses increase along with the diameters .The extinc-tion coefficients of AlF 3 layers at the edge position are 1.8 times of that at the center , and surface roughness are 17.7 times of that at the center .The results suggest that for the coating on the surface of spherical ele-ment, the difference in optical loss along the diameter caused by steam incident angles should be considered .