Anti-reflection coating on calcium fluoride substrate using ion-assisted deposition

摘要

The IR AR coating is of great importance in contemporary optics industry, thus in this theme we investigate deposition processes of anti-reflection coatings on calcium fluoride substrate using ion-assisted deposition, including single layer of ZnSYbF_3 and a multilayer coating of AR. These thin films are produced by thermal evaporation using ion-assisted deposition, and with their optical characteristics measured and calculated, we analyzed the influence of ion source parameters on coatings such as anode voltage, anode current, argon flow, and so on. Based on research upon, we finally put forward the appropriate parameters to deposition antireflection coating on calcium fluoride substrate, in which the anode voltage and anode current play important roles in influencing the index of refraction and extinction coefficient of single layer of ZnS and YbF_3 coatings in the infrared wavelength. Moreover, because of the ambient moisture, the anti-reflection coating deposition only work for ZnS and YbF_3, but a Y_2O_3 layer can be added to protect the anti-reflection coating. In the end, we measured the coating with spectrometer and find out its average transmission reached 99.8%, which can satisfy the practical requirement.