The optical set up comprises only three elements (see figure below). A cooled torroidal mirror (M1), 11.8m away from the source, collimates the output beam deflecting it vertically. Practically all radiation with energies above 60 eV is absorbed. After diffraction on a plane grating (G) with a constant deviation of 130° a second mirror (M2) refocuses the beam onto a fixed exit slit (not shown). The only movement for energy tuning is a single axis rotation of the grating. Incidence angles on all elements are above 65° providing a much higher reflectivity than that obtained in a normal-incidence concept.