Abstract: A method of depositing an optical coating with a predetermined refractive index n and a thickness d, using a first source material having a refractive index n.sub.H greater than n and a known rate of deposition r.sub.H and a second source material having a refractive index n.sub.L less than n and a variable rate of deposition r.sub.L, requires calculating the deposition rate r.sub.L according to the equation ##EQU1## and depositing the first source material at the rate r.sub.H and the second source material at the rate r.sub.L for a time interval T=d/(r.sub.H +r.sub.L). A method of depositing a gradient index optical coating with a predetermined refractive index profile n(d) which is a function of depth d in the coating uses a first source material having a refractive index n.sub.H and a known rate of deposition r.sub.H and a second source material having a refractive index n.sub.L and a variable rate of deposition r.sub.L.