Assembly of confocal Silicon Pore Optics mirror modules

The mirror modules composing Athena's X-ray optics are made with the Silicon Pore Optics (SPO) technology. SPO is produced as stacks of 38 mirror plates, which are paired to form X-ray Optics Units (XOUs) following a modified Wolter I geometry. In the current design, a mirror module is composed of two confocal XOUs glued in between a pair of brackets that freeze the configuration and provide interfaces to the mirror structure. Mirror modules are assembled at the XPBF2 beamline of PTB at the synchrotron radiation facility BESSY II, using dedicated jigs. In this paper we present the latest developments regarding the assembly of confocal mirror modules for Athena with an emphasis on alignment tolerances and gluing accuracy.