Ultra shallow silicon EUV gratings fabricated via ion irradiationKaufmann, Johannes; Ciesielski, Richard; Freiberg, Katharina; Walther, Markus; Fernández Herrero, Analía; Lippmann, Stephanie; Soltwisch, Victor; Siefke, Thomas; Zeitner, Uwe
doi: 10.1117/12.3055797pmid: N/A
Diffraction gratings operating at near-normal incidence in the extreme ultraviolet range (EUV) require structure heights that are extremely challenging to produce via conventional etching techniques. Here, we present an alternative fabrication approach utilizing swelling caused by ion irradiation. Fast processing speeds on scales of tens of square cm are enabled by a broad ion beam in combination with a photoresist mask. By utilizing this process with molecular nitrogen ions with an energy of 40 keV we show the fabrication of binary lamellar gratings with pitches in the range of 400nm to 2μm. Realised structure heights range from 1.7nm to 20nm, which is relevant to applications in the EUV. An investigation of technological challenges gives insight into parameters necessary for a control of structure height with accuracy in the angstrom range.
Calculation of effective collecting area of a lobster eye with respect to full point spread functionTichý, Vladimír; Hudec, René
doi: 10.1117/12.3058295pmid: N/A
The lobster eye shows a specific point-spread function (PSF). The PSF consists of a cross and spots around the cross. The cross consists of focal spot and four arms. The analysis how much radiation is collected to each of these parts is presented in this paper. General equation is derived and it is applied to reflectivity models. Results are compared to ray-tracing simulations. The results have an important consequence: If a smart image processing algorithm (e.g. deconvolution) that utilizes not only the focal spot but all the focal cross is used then the utilized collecting area of the optics can be significantly increased.
Development of computational framework for optimizing broadband x-ray multilayer coatings for high-energy astrophysicsDixit, Kirtan P.; Gurgew, Danielle N.; Singam, Srikanth Panini; Gaskin, Jessica A.
doi: 10.1117/12.3058427pmid: N/A
The design of broadband, high-angular-resolution X-ray optics is pivotal for advancing astronomical instrumentation, particularly in missions targeting high-energy astrophysical phenomena across the 2–200 keV range. Depth-graded multilayer (DGM) coatings are a robust approach for achieving high reflectivity in this band. These coatings use a depth-dependent variation in bilayer thickness to enable constructive interference across a wide spectral range. Their performance depends on factors such as the total number of layers, the minimum and maximum thicknesses, and how gradually the thickness changes with depth. Conventional multilayer design workflows rely heavily on manual tuning or iterative experimental procedures - both resource-intensive and limited in exploring large parameter and material spaces. Approaches such as differential evolution (DE) and Monte Carlo tree search (MCTS) have been employed to improve multilayer prescriptions for hard X-ray reflectors, offering significant progress in algorithmic coating design. Nevertheless, these methods typically require multiple re-optimizations for each geometry, material pair, or scientific goal, which limits scalability. In this work, we present a machine-learning-assisted framework for DGM design that generalizes across energy ranges, grazing incidence angles, and material combinations. The system is trained on a large library of physics-based reflectivity simulations and learns to predict multilayer design parameters that maximize average reflectivity over a target energy band. Once trained, the model enables rapid inverse design without the need for repeated optimization cycles. These machine learning predictions can also be optionally refined using local or global optimizers, making the framework extensible and adaptive. This hybrid simulation-machine learning approach represents a promising advancement toward scalable, flexible, and high-performance DGM coating design for future high-energy astrophysics missions.
A visitor experiment on astronomical x-ray optics for the “Deutsches Röntgen-museum”Stanik, Eva; Pregler, Jan; Döhring, Thorsten; Kätker, Anna; Busch, Uwe; Friedrich, Peter
doi: 10.1117/12.3056291pmid: N/A
The “Deutsches Röntgen-Museum” in Remscheid (Germany) is the unique institution worldwide that researches and documents the life and work of the first Nobel Prize winner in physics, Wilhelm Conrad Röntgen, and the effects of his discovery of x-rays. As an integral part of the museum, the RöLab laboratory offers visitors the opportunity to gain practical experience in x-rays, optics and technology through own experiments. As part of a joint development project, students from Aschaffenburg University of Applied Sciences are currently designing a visitor experiment on astronomical x-ray optics for the museum's Röntgen laboratory. An optical set-up with visible light illustrates the focusing principle of x-ray telescopes, e. g. for wide-angle optics based on the lobster-eye principle. Display boards explain the optics of various types of telescopes with accompanying text and corresponding illustrations. Modern x-ray observatories such as CHANDRA, XMM-Newton and eROSITA are presented clearly. Once implemented, the new visitor experiment inside the “Deutsches Röntgen-Museum” aims to inspire young researchers with enthusiasm for the fascinating world of x-ray optics and x-ray astronomy.
Polydopamine: a bio-inspired polymer for x-ray mirror coatings and other technical applicationsKhropost, Diana; Riethmüller, Franziska; Döhring, Thorsten; Flachs, Dennis; Hülagü, Deniz; Hertwig, Andreas; Cotroneo, Vincenzo; Gibertini, Eugenio
doi: 10.1117/12.3056298pmid: N/A
Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as one of the “hormones of happiness”, thin polymer films of polydopamine (PDA) also have interesting technical properties. PDA is a very strong glue that sticks on almost everything, even under water. In nature, PDA is found in the byssal thread cuticles of mussels. When produced by dip-coating, the self-organizing PDA layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometres thickness only. Here we present an optimized preparation regime as derived from polymerization analysis through absorption spectroscopy. One application is the use of thin PDA overcoatings to increase the soft X-ray reflectivity of astronomical X-ray mirrors. Furthermore, we give an outlook to other technical applications for this interesting material, presenting this bio-inspired organic polymer as an innovative technical solution for the future, with applications such as PDA-based super-capacitors and its promising role in enhancing separator materials for batteries.