Sputter deposition was used to obtain optical thin films of TiO2, ZrO2, and CeO2 having (1) refractive indices greater than those obtained by vacuum vapor deposition techniques, (2) improved abrasion resistance, and (3) better substrate adherence. SiO2 and SiO films with indices of 1.4 and 1.9, respectively, were obtained, but reproducible intermediate indices were not. Films with intermediate refractive indices showed absorption at the short wavelength end of the visible spectrum. Deposition of MgF2 by partial pressure of Freon 14 was moderately successful. The relationship between thickness and time was sufficiently accurate to monitor film thickness. Thickness evaluation with TiO2, CeO2, and SiO2 indicated that reproducibility was within ±2% of desired optical thickness.
William J. Coleman, "Evolution of Optical Thin Films by Sputtering," Appl. Opt. 13, 946-951 (1974)