The mastering of an industrial process to economically manufacture high precision aspherics is of utmost importance to obtain high performance infrared systems in the 3 to 5 and 10 to 13 i2m ranges. The research and the results of such a process are presented. Starting with a spherical surface very close to the desired profile, material is deposited by vacuum evaporation. Between the rotating lens and the source, one or several masks of specific shapes determines the aspherical curvature profile. Up to 50 um of material can thus be added to a sphere, with a precision of 0.1 µm.