Preparation of enhanced Al/MgF₂ vacuum ultraviolet reflective coatings using electron-beam evaporation

Aluminum (Al)-based metal-dielectric composite coatings play a crucial role in the production of vacuum ultraviolet (VUV) optical components and laser systems. In the short-wavelength range of the VUV region, there is a high demand for practical Al-based coatings with high reflectivity, which imposes strict requirements on the preparation process. Key parameters of the preparation process, such as deposition rate, film thickness, and deposition temperature, significantly influence the growth and short-wavelength VUV optical properties of the coatings. In this study, we utilized electron-beam evaporation technology to prepare magnesium fluoride (MgF2) protected Al coatings for short-wavelength VUV reflection. We explored the impact of the aforementioned key process factors on the coatings’ properties and improved the reflectivity of the coatings in the short-wavelength VUV range, achieving reflectivity above 85% at the wavelength of 121.6 nm.