Double multilayer monochromators for upgraded ESRF beamlines

Recently, several upgraded ESRF beamlines have become operational. Some of them include Double Multilayer Monochromators (DMM) to reduce the heat load on downstream optics or to benefit from increased flux compared to crystal optics. In some cases the bandwidth of the DMM has to stay below 0.5%. Such multilayers require an elevated number of layers, materials with moderate electron density, and a coating uniformity close to 0.1%. These boundary conditions impose severe constraints on the performance of the deposition system. This work will highlight successful results and discuss persisting issues and potential approaches for technical improvements.