The mirror modules composing Athena’s X-ray optics are made with the Silicon Pore Optics (SPO) technology.
SPO is produced as stacks of 38 mirror plates, which are paired to form X-ray Optics Units (XOUs) following a
modified Wolter I geometry. In the current design, a mirror module is composed of two confocal XOUs glued in
between a pair of brackets that freeze the configuration and provide interfaces to the mirror structure. Mirror
modules are assembled at the XPBF2 beamline of PTB at the synchrotron radiation facility BESSY II, using
dedicated jigs. In this paper we present the latest developments regarding the assembly of confocal mirror
modules for Athena with an emphasis on alignment tolerances and gluing accuracy.
The Silicon Pore Optics (SPO) technology has been established as a new type of X-ray optics and will enable future X-ray observatories such as Athena and Arcus. SPO is being developed at cosine Research B.V. together with the European Space Agency (ESA) and academic as well as industrial partners. For Athena, about 150,000 mirror plates are required. With the technology spin-in from the semiconductor industry, mass production processes can be employed to manufacture rectangular SPO mirror plates in high quality, large quantity and at low cost. Over the last years, several aspects of the SPO mirror plates have been reviewed and undergone further developments in terms of effective area, intrinsic behavior of the mirror plates and mass production capability. The paper will provide an overview of most recent SPO plate designs, mirror plate production status and plan forward including reflective coating process as well as mass production developments.
Athena, the largest space-based x-ray telescope to be flown by the European Space Agency, uses a new modular technology to assemble its 2.5 m diameter lens. The lens will consist of several hundreds of smaller x-ray lenslets, called mirror modules, which each consist of up to 76 stacked mirror pairs. Those mirror modules are arranged in circles in a large optics structure and will focus x-ray photons with an energy of 0.5 to 10 keV at a distance of 12 m onto the detectors of Athena. The point-spread function (PSF) of the optic shall achieve a half-energy width (HEW) of 5” at an energy of 1 keV, with an effective area of about 1.4 m2, corresponding to several hundred m2 of super-polished mirrors with a roughness of about 0.3 nm and a thickness of down to 110 µm. This paper will present the status of the technology and of the mass production capabilities, show latest performance results and discuss the next steps in the development.
The European Space Agency (ESA) is developing the Athena (Advanced Telescope for High ENergy Astrophysics) X-ray telescope, an L-class mission in their current Cosmic Vision cycle for long-term planning of space science missions. Silicon Pore Optics (SPO) are a new type of X-ray optics enabling future X-ray observatories such as Athena and are being developed at cosine with ESA as well as academic and industrial partners. These high-performance, modular, lightweight yet stiff, high-resolution X-ray optics shall allow missions to reach unprecedented combination of large effective area, good angular resolution and low mass. As the development of the Athena mission progresses, it is necessary to validate the SPO technology under launch conditions. To this end, ruggedisation and environmental testing studies are being conducted to ensure mechanical stability and optical performance of the optics before, during and after launch. In this paper, we report on the results of our completed environmental testing campaigns on mirror modules of middle radius (about 700 mm) of curvature. In these campaigns, each mirror module is first integrated then submitted to sine and random vibration tests, as well as shock tests, all in accordance with the upcoming Ariane launch vehicle and the mission requirements. Additionally, the mirror modules are characterized with X-ray before and after each test to verify the optical performance remains unchanged.
Athena, the largest space-based x-ray telescope to be flown by the European Space Agency, uses a revolutionary new modular technology to assemble its 2.6 m diameter lens. The lens will consist of several hundreds of smaller x-ray lenslets, called mirror modules, which each consist of about 70 mirror pairs. Those mirror modules are arranged in circles in a large optics structure and will focus x-ray photons with an energy of 0.5 to 10 keV at a distance of 12 m onto the detectors of Athena. The point-spread function (PSF) of the optic shall achieve a half-energy width (HEW) of 5” at an energy of 1 keV, with an effective area of about 1.4 m2, corresponding to several hundred m2 of super-polished mirrors with a roughness of about 0.3 nm and a thickness of only 150 µm. Silicon Pore Optics (SPO), using the highest grade double-side polished 300 mm wafers commercially available, have been invented to enable such telescopes. SPO allows the cost-effective production of high-resolution, large area, x-ray optics, by using all the advantages that mono-crystalline silicon and the mass production processes of the semi-conductor industry provide. 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 present the status of the technology and of the mass production capabilities, show latest performance results and discuss the next steps in the development.
Sentinel-4/UVN is a high resolution UVN (UV-VIS-NIR) spectrometer system, being developed within the framework of the Copernicus programme, to support operational monitoring of air quality and climate over Europe and adjacent regions, through accurate atmospheric measurements of trace gas concentrations and aerosols. Stray light is one of the main drivers of the instrument performance. We have developed a stray light correction analysis framework, applicable to a wide range of spectrometer systems, to provide input for selecting the right correction method(s) and specifying calibration measurements, well before the on-ground calibration campaign. This was accomplished by using the instrument design parameters and simulated instrument response to evaluate the S4-UVN stray light performance, before and after stray light correction.
This paper presents the developed framework and a stray light correction sensitivity analysis performed for Sentinel-4/UVN. The analysis results indicate that an iterative convolution correction algorithm can reduce stray light levels in case of smooth stray light, such as diffraction and scattering. The observed fast convergence of the algorithm suggests that a single iteration may suffice in many cases. The study shows that calibration uncertainties should be carefully considered during the preparation for the on-ground calibration campaign, as they can significantly degrade the correction quality.
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.
The European Space Agency (ESA) is developing the Athena (Advanced Telescope for High ENergy Astrophysics) X-ray telescope, an L-class mission in their current Cosmic Vision cycle for long-term planning of space science missions. Silicon Pore Optics (SPO) are a new type of X-ray optics enabling future X-ray observatories such as Athena and are being developed at cosine with ESA as well as academic and industrial partners. These high-performance, modular, lightweight yet stiff, high-resolution X-ray optics shall allow missions to reach an unprecedentedly large effective area of several square meters, operating in the 0.2 to 12 keV band with an angular resolution better than 5 arc seconds. As the development of Athena mission progresses, it is necessary to validate the SPO technology under launch conditions. To this end, ruggedisation and environmental testing studies are being conducted to ensure mechanical stability and optical performance of the optics before, during and after launch. At cosine, a facility with shock, vibration, tensile strength, long time storage and thermal testing equipment has been set up to test SPO mirror module components for compliance with the upcoming Ariane launch vehicle and the mission requirements. In this paper, we report on the progress of our ongoing investigations regarding tests on mechanical and thermal stability of mirror module components such as single SPO stacks complete mirror modules of inner (R = 250 mm), middle (R = 737 mm) and outer (R = 1500 mm) radii.
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.
Silicon Pore Optics is the X-ray mirror technology selected for the European Space Agency's Athena X-ray observatory. We describe the X-ray testing and characterization cycle that the optics are subjected to at the PTB's X-ray Pencil/Paraller Beam Facility (XPBF) 1 and 2 beamlines at the synchrotron radiation facility BESSY II. Individual stacks are measured with a pencil beam to determine their optical quality and the orientation of the optical axis. Using metrics based on X-ray and manufacturing metrology, stacks are then paired in primary-secondary Wolter-I-like systems, that are in turn characterized to determine their optical performance. Finally, four stacks, two primaries and two secondaries, are assembled into a mirror module, that is also characterized, with pencil and wide X-ray beams. At each step models, metrology, and software are combined to arrive at the relevant parameters. We describe the methods used, and illustrate how the performance of imaging pairs can be described in terms of stack-level parameters.
Silicon Pore Optics (SPO) is an enabling technology for future large-area space-based X-ray observatories, such as ESA's Athena mission and NASA's Arcus candidate mission. SPO consist of stacks of thin silicon mirrors, which together provide a large effective area with a relatively low mass. Stacks are produced by custom robots that bend the mirrors into the design shape and stack them. We discuss the latest developments in improving the stacking process. The main challenge is to minimize shape deviations in order to optimize the imaging resolution of the optic. During the stacking process, the shape of each plate is measured directly after it is added to a stack. This metrology allows us to quickly quantify the effect of different stacking recipes, which streamlines the development. We discuss recent improvements in reducing excess meridional curvature. Furthermore, we prepare for mass-production by optimizing the robotics for performance and reproducibility.
Silicon Pore Optics (SPO) has been established as a new type of x-ray optics that enables future x-ray observatories such as Athena. SPO is being developed at cosine with the European Space Agency (ESA) and academic and industrial partners. The optics modules are lightweight, yet stiff, high-resolution x-ray optics, that shall allow missions to reach an unprecedentedly large effective area of several square meters, operating in the 0.2 to 12 keV band with an angular resolution better than 5 arc seconds. In this paper we are going to discuss the latest generation production facilities and we are going to present results of the production of mirror modules for a focal length of 12 m, including x-ray test results.
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