真空室内金属粒子污染是降低激光薄膜性能的一个重要因素。采用高真空残余气体分析仪,对薄膜沉积过程中的气氛进行分析。发现由黄铜制作的加热灯架在工作时会分解出Zn,在这种条件下沉积薄膜,会使薄膜中掺入金属杂质,导致薄膜激光破坏阈值降低。采用表面分析技术对薄膜的组分进行分析,证实薄膜中锌杂质的存在。激光破坏实验证明,含有锌杂质的薄膜的破坏阈值明显降低。

During the coating process, the metal contamination in the vacuum chamber is one of the significant factors to reduce the optical properties of thin films. The gas composition during coating process was tested by high-vacuum residual gas analyser. It is found that when applying brass pedestal in the vacuum chamber, zinc will sublime from the pedestal under high temperature and deposit in the thin film, thus reducing its laser-induced damage threshold (LIDT). The composition of the coatings was studied by surface analysis technology which proved the zinc impurity in the coatings. And the laser-induced damage experiment also showed that its LIDT was distinctly reduced.