The indirect hot slumping technology is being developed at Max-Planck-Institute for extraterrestrial Physics (MPE) for the manufacturing of lightweight astronomical X-ray telescopes. It consists of a thermal shaping process to replicate the figure of a suitable mould into segments of X-ray mirror shells made by glass. Several segments are aligned and mounted into elemental modules, a number of which is then assembled together to form the telescope. To obtain mirror segments of high optical quality, the realization of the slumping thermal cycle itself is of fundamental importance, but also the starting materials, primarily the mould and the glass foils, play a major role. This paper will review the MPE approach in the slumping technology development and will then concentrate on the glass, with particular regards to the problem of thickness variation.
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