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氟化镁是广泛用于镀增透膜和其它膜层的唯一的低折射率材料。大家知道,用钽、钨或钼舟以及电子射线可方便地使它蒸发。实验表明,在冷的基片上真空淀积的氟化镁膜,其气孔率很大,因而机械强度很小(仅Ⅲ级强度)。为了提高氟化镁膜的强度,过去采取将基片加热到300℃再蒸镀的方法。但是,在一系列条件下,当对表面精度要求特别高时,加热基片是不适宜的,甚至根本不能允许。此外,在真空中加热基片,镀后还要使零件冷却下来,这就增加了工序和工时。因此,人们对于在冷的基片上镀制机械强度高的氟化镁膜,是很感兴趣的。
Magnesium fluoride is the only low refractive index material widely used for AR coatings and other coatings. We all know that with tantalum, tungsten or molybdenum boat and electron beam can easily make it evaporate. Experiments show that the vacuum deposition of magnesium fluoride film on a cold substrate, its porosity is very large, so the mechanical strength is very small (only grade strength). In order to increase the strength of the magnesium fluoride film, a method of heating the substrate to 300 ° C and then vapor-depositing was used. However, under a series of conditions, when the surface accuracy is particularly high, heating the substrate is not suitable, or even not allowed at all. In addition, the substrate is heated in a vacuum and the parts are allowed to cool down after plating, which increases the number of processes and man-hours. Therefore, people are interested in plating a mechanically strong magnesium fluoride film on a cold substrate.