Multilayer coating of XTP telescope mirrors

We present the coating of depth-graded W/Si multilayers on the thin glass substrates for telescopes in X-ray timing and polarization mission. The multilayer consists of several hundred bilayers in an optimized graded power law design with stringent requirements on uniformity and interface width. We introduce the details of the planar magnetron sputtering facility including the optimization of the deposition process. Results are presented on the uniformity, interface width, reflectivity and the fabrication of a 200-bilayers depth graded multilayer working at hard X-ray energies.