Stacking of silicon pore optics for IXO

Abstract

Silicon pore optics is a technology developed to enable future large area X-ray telescopes, such as the International Xray Observatory (IXO), a candidate mission in the ESA Space Science Programme 'Cosmic Visions 2015-2025'. IXO uses nested mirrors in Wolter-I configuration to focus grazing incidence X-ray photons on a detector plane. The IXO mirrors will have to meet stringent performance requirements including an effective area of ~3 m 2 at 1.25 keV and ~1 m 2 at 6 keV and angular resolution better than 5 arc seconds. To achieve the collecting area requires a total polished mirror surface area of ~1300 m 2 with a surface roughness better than 0.5 nm rms. By using commercial high-quality 12" silicon wafers which are diced, structured, wedged, coated, bent and stacked the stringent performance requirements of IXO can be attained without any costly polishing steps. Two of these stacks are then assembled into a co-aligned mirror module, which is a complete X-ray imaging system. Included in the mirror module are the isostatic mounting points, providing a reliable interface to the telescope. Hundreds of such mirror modules are finally integrated into petals, and mounted onto the spacecraft to form an X-ray optic of four meters in diameter. In this paper we will present the silicon pore optics assembly process and latest X-ray results. The required metrology is described in detail and experimental methods are shown, which allow to assess the quality of the HPOs during production and to predict the performance when measured in synchrotron radiation facilities.

X-Ray Pore Optics Technologies and Their Application in Space Telescopes

“…A technology programme is being implemented, addressing further improvement of the angular resolution to reach the requirement of IXO, the predevelopment of mass production equipment necessary for large telescope implementations and, finally, the environmental qualification of SPO modules [35,[53][54][55][56].…”

Toward active x-ray telescopes II

“…Figure 5 left panel displays a prototype silicon-pore optic 10,11,12 (SPO) fabricated (largely robotically 13 ) by cosine BV for ESA's European Space Research & Technology Centre (ESTEC). The mirror module contains dozens of diced, ribbed, and wedged silicon plates, which are robotically stacked into the X-ray Optics Unit (XOU).…”

Silicon pore optics development for ATHENA

“…The SPO development in the past focused on demonstrating in a holistic approach the entire production chain, from wafer up to optical bench level, at one focal length and radius, on which we reported extensively in [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. This included a complete set of environmental tests on mirror module level, resulting in a technology readiness level (TRL) of ~5 at the current stage.…”