Production of x-ray multilayer coatings by plasma sputtering

X-ray optical elements have been coated with multilayers using a DECR aArgon plasma sputtering technique. In a number of applications, e.g. beam focusing, a lateral gradient of the multilateral period is required. This is obtained by scanning a set of sputter targets at controlled speed with respect to the stationary mirror substrate. The target velocities are inferred from a model that accounts for the plasma ion density and the spatial flux distribution above each target. Thickness profiles have been produced over 300 mm by 50 mm with a precision better than 1%. Recent results on the deposition of M/B4C multilayers, where M = Cr, Ni, Mo, Ru, and W, are presented.