LAUSR

Abstract. Lynx is the future x-ray observatory with superb imaging capabilities (<1  arc sec half-energy width) and large throughput (2  m2 effective area @ 1 keV), which is being considered in the U.S. to take over Chandra. The implementation of the x-ray mirror module represents a very challenging aspect, and different approaches are being considered. Thin and low-weight substrates, working in grazing incidence configuration, are necessary to meet the severe mass constraints, but they have to also preserve the requirement of an excellent angular resolution. The use of monolithic glass (fused silica) shells is an attractive solution, provided that their thickness is kept very small [<4  mm for mirror shells up of 3-m diameter]. We present the optomechanical design of the Lynx mirror assembly based on this approach, together with the ongoing technological development process. In particular, we discuss the figuring process, which is based on direct polishing followed by an ion-beam figuring correction. A temporary structure is specifically devoted to support the shell during the figuring and polishing operations and to manage the handling of the shell through all phases up to integration into the final telescope supporting spoke wheel. The results achieved so far on a prototype shell will be discussed.