Each of the three X-ray telescopes on board XMM-Newton consists of 58 Wolter I grazing-incidence mirrors which are nested in a coaxial and cofocal configuration. The design of the optics was driven by the requirement of obtaining the highest possible effective area over a wide range of energies, with particular emphasis in the region around 7 keV. Thus, the mirror system had to utilize a very shallow grazing angle of 30' in order to provide sufficient reflectivity at high energies. The telescopes focal length is 7.5 meters and the diameter of the largest mirrors is 70 cm, to be compatible with the shroud of the launcher. Each telescope includes, apart from the mirror modules, baffles for visible and X-ray stray-light suppression and an electron deflector for diverting soft electrons. Two of the telescopes carry a Reflection Grating Array (RGA).
58 nested Wolter I