Recent Results on Manufacturing of Segmented X-Ray Mirrors with Slumped Glass

Future X-ray missions are aiming at large mirror collecting areas of the order of several square meters. This is obtained with mirror assemblies composed of a large number of segments. The angular resolution of each one must be measured separately down to 1 arcsec. The mass limits imposed by the launchers require low weight and high stiffness materials. In this context we have focused our recent studies on the manufacturing of thin glass mirror segments. These mirrors are made from sheet glass which can be shaped in a high-precision slumping process to e. g. a Wolter-I figure. The excellent surface roughness of the sheet glass chosen is conserved during the slumping process and the final figure corrections with ion beam figuring. The influence of several parameters of the process, such as glass and mould material, heating and cooling, has been measured and controlled with adequate metrology. In this paper we describe our current efforts which are aiming at the production of a Wolter-I demonstration model - preferentially with parabola and hyperbola in one piece - made of thin sheet glass.