The Silicon Pore Optics (SPO) technology has been established as a new type of X-ray optics enabling future X-ray observatories such as ATHENA. SPO is being developed at cosine together with the European Space Agency (ESA) and academic as well as industrial partners. The SPO modules are lightweight, yet stiff, high-resolution X-ray optics, allowing missions to reach a large effective area of several square meters. These properties of the optics are mainly linked to the mirror plates consisting of mono-crystalline silicon. Silicon is rigid, has a relatively low density, a very good thermal conductivity and excellent surface finish, both in terms of figure and surface roughness. For Athena, a large number of mirror plates is required, around 100,000 for the nominal configuration. With the technology spin-in from the semiconductor industry, mass production processes can be employed to manufacture rectangular shapes SPO mirror plates in high quality, large quantity and at low cost. Within the last years, several aspects of the SPO mirror plate have been reviewed and undergone further developments in terms of effective area, intrinsic behavior of the mirror plates and mass production capability. In view of flight model production, a second source of mirror plates has been added in addition to the first plate supplier. The paper will provide an overview of most recent plate design, metrology and production developments.
Silicon Pore Optics (SPO) uses commercially available monocrystalline double-sided super-polished silicon wafers as a basis to produce mirrors that form lightweight and stiff high-resolution x-ray optics. The technology has been invented by cosine and the European Space Agency (ESA) and developed together with scientific and industrial partners to mass production levels. SPO is an enabling element for large space-based x-ray telescopes such as Athena and ARCUS, operating in the 0.2 to 12 keV band, with angular resolution requirements up to 5 arc seconds. SPO has also shown to be a versatile technology that can be further developed for gamma-ray optics, medical applications and for material research. This paper will summarise the status of the technology and of the mass production capabilities, show latest performance results and discuss the next steps in the development.
Silicon Pore Optic (SPO) is the X-ray mirror technology selected for the Athena X-ray observatory. The optic is modular; in the current design, it is made of about 700 co-aligned mirror modules. SPO is produced as stacks of 35 mirror plates, which are then paired to form X-ray Optics Units (XOUs) following a modified Wolter I geometry. A mirror module is composed of two confocal XOUs bonded in between a pair of brackets allowing interfacing to the mirror structure. Mirror modules are assembled using the XPBF 2.0 beamline of PTB at the synchrotron radiation facility BESSY II, using pencil beam and dedicated jigs. In this paper we present the challenges and solutions related to making confocal mirror modules.
Mission studies and technology preparation for the ATHENA (Advanced Telescope for High ENergy Astrophysics) [1- 5] mission are continuing to progress. The X-ray optics of this future space observatory are based on the Silicon Pore Optics (SPO) technology [6-58], and is being evolved in a joint effort by industry, research institutions and ESA. The SPO technology benefits from substantial investments made by the semiconductor industry, and spins-in materials, processes and equipment into the development of novel X-ray optics. A comprehensive Technology Development Plan (TDP) is being implemented, funded by ESA and involving a large number of experts in key areas ranging from micro machining of Silicon, over sophisticated automation and robotic systems, to hybrid manufacturing. The performance, environmental compatibility and serial automated production and testing are being addressed in parallel, aiming at the demonstration of the required technology readiness for the ATHENA Mission Adoption Review (MAR) expected by the end of 2021. A formal Technology Readiness Assessment is in place and is being currently exercised in preparation of the ATHENA Mission Formulation review (MFR). The programmatics for the flight model implementation is being defined in detail, and preparations are starting for the design and implementation of the necessary facilities. An overview of the ATHENA optics technology preparation, the technology readiness assessment and the related activities is provided.