X-ray evolving universe spectroscopy mission (XEUS): requirements of the x-ray focal plane instruments

The requirement set for the focal plane instruments on XEUS area addressed. The rationale for the selection of three focal plane instruments, a wide field imager with modest spectral resolution and tow narrow field imagers with high spectral resolution, is given. The principles and designs of all three instrument are shortly explained and their expected performances given. The cooling of the focal plane instruments, based on mechanical cryocoolers, is described as well.