Direct hot slumping of thin glass foils for future generation x-ray telescopes: current state of the art and future outlooks

Abstract

To significantly improve the performances of the current X-ray observatories, the next generation of X-ray telescopes has to be characterized by a large effective area (A eff ~ 2 m 2 at 1 keV) and angular resolution better than 5 arcsec. The large dimension implied by these requirements forces the use of a modular approach, splitting the optics into segments. Moreover, lightweight materials, such as glass, have to be selected for the segmented optics in order to maintain a manageable weight for the optics. Since 2009 we are developing a direct hot slumping technique assisted by pressure, in which the glass optical surface is in contact with the mould and a pressure is applied in order to force the glass to copy the mould shape. A cold slumping step is used then to integrate the mirror segments into the final Wolter-I configuration. We present the state of the art of our hot slumping technology, comparing the results obtained with different glass types and mould materials. We also provide an overview of the possibilities of this technology also in view of future developments.

Optics technology for large-aperture space telescopes: from fabrication to final acceptance tests

“…In order to explore SMBHs hidden by thick absorbers (column density of neutral hydrogen (HI) >10 23 H∕cm 2 ), an energy range of 60-80 keV (in original rest frame) is required along with sufficient spatial resolution of 10-20 arcsec. Such attempts of these measurements have been done by balloon experiments, such as the International Focusing Optics Collaboration for μCrab Sensitivity (InFOCμS) [22], and later with the satellites the Nuclear Spectroscopic Telescope Array (NuSTAR) [23], and the International X-ray Astronomy Mission (ASTRO-H/ Hitomi) [24]) with multilayer coatings (Pt/C or W/Si).…”

“…4 are examples of (a) SGO and (b) SPO optical stacks that will be replicated to form the full optical surface. A preliminary SGO technology was used for the optics in NuSTAR [108], while new developments in the technology might be implemented on optics for the ATHENA mission [23,109]. The principle of making an SGO is that of a molded sheet of glass pressed and heated such that either the optical or non-optical surface is in contact with the mold.…”