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Differential deposition and profile coating are two common deterministic fabrication methods for figure correction of high-precision mirrors. The generation of the desired particle distribution on the substrate as the growing function is an important prerequisite, especially for two-dimensional correction. A model of particle distribution considering the etched ring shape, mask structure, and mask distance between the target and substrate is established. The model is verified by deposition experiments using a series of circular holes with different hole sizes and distances of the mask from the substrate. According to the model, a smallest deposition beam width of 2.79 mm can be obtained using a hole with a 3 mm diameter. The shape of the particle distribution gradually changes from convex to concave as the mask moves away from the substrate for different holes. A two-dimensional figure correction of a flat mirror was demonstrated using a hole with a 6 mm diameter. The peak-to-valley (PV) value is reduced from 74.23 nm to 10.09 nm, and the root mean square (RMS) value is reduced from 18.38 nm to 1.36 nm within a 130 mm × 20 mm area. The model could provide useful guidance for high-precision two-dimensional figure correction applications.

Theoretical and Experimental Study of Particle Distribution from Magnetron Sputtering with Masks for Accurate Thickness Profile Control