高反射率193nm Al2O3／MgF2反射膜的实验研究

用电子束热蒸发方法在熔融石英基底上沉积了Al2O3和MgF2两种材料的单层膜，研究了两种材料的光学特性，采用光度法计算并给出了薄膜材料在180～230nm的折射率n／和消光系数k的色散曲线。以两种材料作为高低折射率材料组合，采用1／4波长规整膜系设计并镀制了193nm的高反射膜，反射膜在退火后的反射率在193nm达到96％以上。结果表明在一定工艺条件下Al2O3和MgF2两种材料能够在193nm获得较好的光学性能，适用于高反射膜的制备。

The single-layer films of Al2O3 and MgF2 were deposited upon super polished fused-silica by electron-beam evaporation and were characterized. The subsequent optical constants n and k were reported for the spectral range of 180～230 nm. High-reflectivity (HR) Al2O3/MgF2 mirrors were designed and produced for the wavelength of 193 nm. The annealed mirrors with a reflectance of more than 96% at 193nm were obtained. It was found that the single layers of Al2O3 and MgF2 deposited according to optimized process could get suitable optical properties at 193 nm. And it was easier for HR mirrors to form the oxygen-deficient Al2O3 films than the single layers.