Most applications of x-ray multilayers at modern synchrotron sources require a precise control of the d-spacing over large areas. The grazing incidence geometry causes a long beam footprint. Curved multilayer optics may need steep thickness gradients in order to reflect the full beam at constant photon energy. The tolerable thickness error is far below the intrinsic energy resolution of the multilayer Bragg peak, which is of the order of 1% or less. The recently commissioned ESRF multilayer deposition system can coat surfaces of up to 1000mm long and 150mm wide with a precise thickness distribution. The local particle flux is controlled by both linear motion of the substrates and masking of the particle sources. The thickness profiles are estimated using a numerical model. Corrections can be applied to suppress minor errors. Recent results illustrate both the potential and the limitations of the available deposition technology. A description of present and future applications at 3rd generation synchrotron sources complements this work.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.