XRR scans provide detailed insights into thin film properties, however, the dependence on accurate a priori knowledge necessitates a robust model for solving the inverse problem. Addressing this limitation, XPS proves invaluable in revealing the chemical composition of thin films, improving the accuracy of the XRR model. Combined characterization through OM and XRR is very useful to find visual insights into surface contamination-induced changes when mirrors are stored for long periods in a clean room environment, as might be the case for some astronomical missions. The synergy among these techniques is pivotal for evaluating coating quality for high-energy astronomical telescopes, with a specific focus on NewAthena and upcoming missions. This research not only advances methodologies in this field but also highlights the collaborative power of XRR, XPS, and OM in providing a comprehensive understanding of thin film coatings, emphasizing the importance of pre-coating mirror quality and mitigating contamination effects throughout the optics production process to ensure optimal performance.
In this paper we present our current state-of-the-art SPO plate manufacturing process. Special attention is given to the recent advancements in optimizing and upscaling the dicing process, the laser-ID labelling process, wafer-scale automated measurements of plate critical to quality parameters, as well as the lithography process for reflective coating lift-off. Furthermore, the different wedging methodologies and the shift from wetbench processing to spray processing are introduced. The combined efforts in all of these areas enable a more automated plate manufacturing process, and an increase in optical performance of the telescope.
Using a combination of process development and upgraded machinery, the future flight production scenario for NewATHENA begins to take shape.
The Silicon Pore Optics (SPO) enables the NewAthena mission, delivering an unprecedented combination of good angular resolution, large effective area and low mass. The SPO technology builds significantly on spin-in from the semiconductor industry and is designed to allow a cost-effective flight optics implementation, compliant with the programmatic requirements of the mission.
The NewAthena X-ray optics is highly modular, consisting of hundreds of compact mirror modules arranged in concentric circles and mounted on a metallic optical bench. All aspects of the optics are being developed in parallel, from the industrial production of the mirror plates, over the highly efficient assembly into mirror modules, to the alignment of the mirror modules and their fixation on the optical bench. Dedicated facilities are being built to measure the performance of the NewAthena X-ray telescope optics, demonstrating their compatibility with the environmental and scientific requirements.
An overview is provided of the activities preparing the implementation of the NewATHENA optics.
We present in this paper the status of the optics production and illustrate not only recent X-ray results but also the progress made on the environmental testing, manufacturing and assembly aspects of SPO based optics.
A key aspect of the thin film coating development for the NewATHENA X–ray optics, is to determine the adhesion efficiency and the residual stress limitation of the coatings on silicon substrates. To do so, we magnetron sputtered different layer thicknesses of chromium layers underneath iridium/carbon bilayer and linear graded multilayer coatings. The samples were characterized using X–ray Reflectometry (XRR) to derive the thickness and micro–roughness. The residual stress was assessed by profilometry using a Dektak 150 stylus profilometer. The curvature of the samples before and after coating, along with the total film thickness derived from XRR, was used to evaluate the residual stress.
ESA’s Athena mission will use silicon pore optics, in which the optics assembly consists of pairs of mirror plates stacked into mirror modules. This paper presents a study of the angular resolution of Athena, using several candidate variants of mirror curvature and wedging. Results were achieved by ray-tracing these variants of Athena’s optics with the ray-tracing software SPORT.
The study shows that all polynomial variants yield a PSF below 1” on-axis, at all energies between 0.1 and 12 keV. The secondary-only polynomial variants perform best, for both on- and off-axis point sources. Of these variants, the wedging 0/2 variant is shown to generally yield superior angular resolution at higher energies, the -1/1 variant at lower energies.
A ray-tracing analysis using the Crab Nebula as an observation target was also performed. A 2D Fourier analysis was applied to the resulting focal plane responses to determine their angular resolution. This analysis indicates the angular resolution of all polynomial variants to be below 1”, at all but the highest energies. It also shows, though to a lesser extent, that the secondary-only polynomial variants perform best in most circumstances. Nevertheless, this second analysis requires further investigation for a more conclusive outcome.
The preparations are ongoing at PANTER, ESA, cosine and Media Lario to perform complex opto-thermo-mechanical tests of the two full scale 1/6th sectors of the final ATHENA mirror assembly structure produced by the potential ATHENA primes Airbus Defence and Space and Thales Alenia Space. For these tests a set of three SPO MMs have been produced following the flight configuration. The MMs will be incorporated into the full scale 1/6th sectors to measure the impact of thermal gradients on the thermoelastic deformation of the structure and therefore the HEW performance. A description of the tests is presented here.
PANTER is also involved in the development, testing, and fabrication of the mirror adapter structure (MAS) to support the 2.6-m diameter ATHENA mirror assembly module demonstrators (MAMD) during the planned x-ray tests at XRCF. A description of the PANTER tests and results will be presented in this paper together with a short overview of the MAS MGSE for XRCF.
The next generation x-ray observatory ATHENA (advanced telescope for high energy astrophysics) requires an optics with unprecedented performance. It is the combination of low mass, large effective area and good angular resolution that is the challenge of the x-ray optics of such a mission. ATHENA is the second large class mission in the science programme of ESA, and is currently in a reformulation process, following a design-to-cost approach to meet the cost limit of an ESA L-class mission.
The silicon pore optics (SPO) is the mission enabler being specifically developed for ATHENA, in a joint effort by industry, research institutions and ESA. All aspects of the optics are being addressed, from the mirror plates and their coatings, over the mirror modules and their assembly into the ATHENA telescope, to the facilities required to build and test the flight optics, demonstrating performance, robustness, and programmatic compliance.
The SPO technology is currently being matured to the level required for the adoption of the ATHENA mission, i.e., the start of the mission implementation phase. The monocrystalline silicon material and pore structure of the SPO provide these optics with excellent thermal and mechanical properties. Benefiting from technology spin-in from the semiconductor industry, the equipment, processes, and materials used to produce the SPO are highly sophisticated and optimised.To overcome these limitations, we started in 2012 to design a facility aimed at generating a broad (170 x 60 mm2), uniform and low-divergent (1.5 arcsec HEW) X-ray beam within a small lab (∼ 9 x 18 m2), to characterize the ATHENA MM. BEaTriX (the Beam Expander Testing X-ray facility) makes use of an X-ray microfocus source, a paraboloidal mirror, a crystal monochromation system, and an asymmetrically-cut diffracting crystal for the beam expansion. These optical components, in addition to a modular low-vacuum level (10-3 mbar), enable to match the ATHENA SPO acceptance requirements.
The realization of this facility at INAF-OAB in Merate (Italy) is now on going. Once completed, BEaTriX can be used to test the Silicon Pore Optics modules of the ATHENA X-ray observatory, as well as other optics, like the ones of the Arcus mission. In this paper we report the advancement status of the facility.
Initially functional requirements on the MM accommodation are presented, with the Effective Area and Half Energy Width (HEW) requirements leading to a MAM comprising (depending on final mirror size selected) between ~700-1000 MMs, co-aligned with exquisite accuracy to provide a common focus. A preliminary HEW budget allocated across the main error-contributors is presented, and this is then used as a reference to derive subsequent requirements and engineering considerations, including: The procedures and technologies for MM-integration into the Mirror Structure (MS) to achieve the required alignment accuracies in a timely manner; stiffness requirements and handling scheme required to constrain deformation under gravity during x-ray testing; temperature control to constrain thermo-elastic deformation during flight; and the role of the Instrument Switching Mechanism (ISM) in constraining HEW and Effective Area errors.
Next, we present the key environmental requirements of the MMs, and the need to minimise shock-loading of the MMs is stressed. Methods to achieve this Ø are presented, including: Selection of a large clamp-band launch vehicle interface (LV I/F); lengthening of the shock-path from the LV I/F to the MAM I/F; modal-tuning of the MAM to act as a low-pass filter during launch shock events; use of low-shock HDRMs for the MAM; and the possibility to deploy a passive vibration solution at the LV I/F to reduce loads.
View contact details