Depositing uniform-thickness coatings on large surfaces by means of electron-beam evaporation in vacuum

This paper discusses a method of increasing the thickness uniformity of multilayer interference coatings deposited by electron-beam evaporation in vacuum onto spherical surfaces by using a mask to screen the current of molecules of the evaporated material. Analytical expressions are obtained for calculating the shape of the mask, and experimental results are presented. Reflective coatings of silicon and zirconium oxides with thickness nonuniformity no greater than ±1.5% are fabricated on a flat substrate 550 mm in diameter in a vacuum apparatus with a chamber 700 mm in diameter.