Abstract: A method and apparatus for depositing spatially substantially uniform layers of material onto a plurality of substrates positioned upon a rotatable tool within a vacuum chamber. The chamber is generally of the type that includes a sealable volume bounded by six orthogonally-arranged chamber walls. Apparatus is provided within the chamber for generating a flux of the coating material of known spatial character. A mask of predetermined shape is engaged to apparatus, including a linkage and a linear translation stage driven by a programmable stepper motor, for controllably advancing it during deposition with respect to the mounted substrate.