Recent advances in propagation-based phase-contrast imaging, such as hierarchical imaging, have enabled the visualization of internal structures in large biological specimens and material samples. However, modulation-based techniques, which provide quantitative electron density information, face challenges when imaging larger objects due to stringent beam stability requirements and detector distortions. Extending the field of view of these methods is crucial for obtaining comparable quantitative results across beamlines and adapting to the smaller beam profiles of fourth-generation synchrotron sources. We introduce a novel image processing technique combining an eigenflat optimization with deformable image registration to address the challenges and enable quantitative high-resolution scans of centimeter-sized objects with multiple-micrometer resolution. We demonstrate the potential of the method by obtaining an electron density map of a rat brain sample 15 mm in diameter despite the limited horizontal field of view of 6 mm of the beamline. This showcases the technique's ability to significantly widen the range of applications of modulation-based techniques in both biological and materials science research.

The Helmholtz-Zentrum Hereon is operating imaging beamlines for X-ray tomography (P05 IBL, P07 HEMS) for academic and industrial users at the synchrotron-radiation source PETRA III at DESY in Hamburg, Germany. The high flux density and coherence of synchrotron radiation enable high-resolution in situ/operando/in vivo tomography experiments and phase-contrast imaging techniques, respectively. Large amounts of 3D and 4D data are collected that are difficult to process and analyze. Recently, we have explored machine learning approaches for the reconstruction, processing and analysis of synchrotron-radiation tomography data. Here, we report on the application of supervised learning for multimodal data analysis to generate a virtual 3D histology, digital volume correlation of 4D in situ tomography data, and instance segmentation. Furthermore, we present findings related to unsupervised learning in the context of semantic segmentation.

This study explores recent developments in quantitative phase-contrast microtomography using Talbot Array Illuminators (TAI) combined with Unified Modulated Pattern Analysis (UMPA). We first compare the performance of the TAI-based method for phase-retrieval with propagation-based imaging (PBI) for analyzing a Mg-10Gd bone implant sample that violates the single-material assumption. Our results demonstrate that the TAI method yields a significantly higher contrast-to-noise ratio (CNR) compared to PBI (101.68 vs. 54.37, an 87% improvement) while maintaining comparable edge sharpness. The TAI method also visualizes a substructure of the degradation layer, which appears comparatively blurred in the PBI images. Additionally, we introduce a hanging-rotation-axis approach for imaging paraffin-embedded samples in an ethanol bath, aiming to reduce edge enhancement artifacts caused by large electron density differences. Preliminary results indicate that the TAI-based images of a paraffin-embedded lymph node show improved uniformity in background intensity, though some additional low-frequency noise is observed. All experiments were conducted at the High Energy Materials Beamline (HEMS), PETRA III, DESY, operated by Hereon. Our findings highlight the potential of TAI-based phase-contrast imaging for complex, multi-material samples and suggest avenues for further optimization of the technique.

Laser welds of electrical components made of highly conductive and light weight aluminum material are essential for the successful transformation of the energy and mobility sector towards renewable energy solutions. To generate a deeper understanding of this important laser welding process and to evaluate process dynamics, it is inevitable to use modern in situ analysis methods. In this work, in situ phase-contrast high-speed videography using synchrotron radiation is used for the first time to analyse the behaviour of different aspect ratios of the vapor capillary (capillary depth/focal diameter) on the stability and thus the porosity of laser welds. The phase contrast method reveals the phase boundaries between solid, liquid, and gaseous material phases and allows the quantitative analysis of the capillary depth and the porosity for different laser parameters and focal diameters. The study is based on the hypothesis that vapor capillaries with high aspect ratio are less influenced by the variation in the degree of energy coupling of the laser radiation, allowing a more stable process without the formation of pores. As result of the investigations, the welding processes with high aspect ratios show no formation of pores and thus higher capillary stability. A value for the aspect ratio of about 10 is identified as a geometric limit, above which pore formation in the processes no longer occurs. The findings are used to derive advice for a quality-specific process design in laser manufacturing processes of metallic materials.

The X-ray phase contrast imaging is a powerful method to understand the fundamental behavior of the melt and keyhole during the laser beam welding process. In this paper, the keyhole-induced vapor capillary formation in the melt pool is investigated by using an adjustable laser beam source. For this purpose, the aluminum A1050 specimen with a thickness of 0.5 mm is molten only with the heat conduction welding regime by using the ring-mode laser beam. Once the specimen is molten through, the core multi-mode laser beam is then applied to vaporize the melt and a transition to keyhole welding regime occurs. Therefore, the core multi-mode laser beam with an intensity value of 33.3 MW/cm 2 is investigated. The correlation between the keyhole-induced vapor capillary and the melt behavior is further investigated in this paper which was recorded with a high sampling rate of 19 kHz. In addition, a theoretical calculation about the keyhole depth is discussed in this paper.

The ongoing development of lasers with integrated beam-shaping features offers new opportunities for research in the field of laser beam welding. Main challenges for laser welding of aluminum alloys, such as AW-5083 or AW-6082, are pore formation and cracking. The locally adapted power distribution has a major influence on the keyhole required for deep penetration welding and therefore on occurring weld defects. To determine the reasons, the use of synchrotron radiation during the welding process enables the visibility of the keyhole shape. This investigation contains an analysis of the keyhole and melt pool shape based on the high-speed video images of the synchrotron radiation. The variation of the power ratio of center beam to ring allows a comparison of the influence of the beam shaping method. To stabilize the keyhole, a temporal power modulation is used for the ring. The results show an influence of the ring mode on the keyhole depth and the melt pool shape. The videos allow an analysis of different mechanisms for pore formation, such as the collapse of the keyhole.

Known as challenging material combination, the welding of aluminium and copper, both with strongly different thermophysical properties, causes joining failures such as pores, cracks or intermetallic phases in the solidified welding area. To investigate the mixing of the materials and the occurrence of pores, the laser welding process is observed with synchrotron radiation which visualizes the phase boundaries between solid, liquid and gaseous material phases. This allows the visualization of pore formation and density differences of the materials inside the melt pool. In this investigation, pore formation in front and bottom of the keyhole is observed. The movement of the bubbles in the melt pool can be tracked until solidification at the material transition. Regarding the intermixing of the materials, the high-speed images show a fluctuating copper flow towards the keyhole and a material mixing over the entire aluminium melt pool depth. By understanding the mechanisms, compensatory measures for an improved process can be developed to enable the usability of aluminium and copper connections, for example in electromobility applications.

Multiple laser surface line hardening experiments on flat samples, made of tempering steel SAE 4140, were carried out under variation of the maximum control temperature in the range of 850 ?C to 1150 ?C at the sample surface. For each temperature, time resolved X-ray diffraction measurements using synchrotron radiation were performed at beamline P05@PETRA III at DESY (Deutsches Elektronen Synchrotron) in Hamburg, Germany. The samples were line hardened using a 4 kW High Power Diode Laser unit at a constant laser feed of 800 mm/min with a specific laser optics under pyrometer control of the maximum surface temperature. A special designed process chamber with 4 symmetrically attached fast silicon micro strip line detectors allows for stress analysis during the process according to the sin2? method in single exposure mode with a measurement frequency of 50 Hz. As a result of the time resolved analyses the elastic strains were separated from thermal ones and near surface local stress evolutions, longitudinal and transverse to the laser track direction in the center of the processed zone, were determined. The in situ experiments were complemented by high spatially resolved postprocess residual stress analyses using conventionally generated X-rays and by metallographic investigations. The results are carefully discussed regarding mechanisms of local stress formation during the laser hardening process and their dependence on the maximum control temperature. The temporal stress course during laser surface line hardening is presented for the first time in both surface parallel directions, where temperature differences in the process zone lead to significant differences in the resulting residual stress profiles. In addition to the common validation of process simulations by comparison with experimentally determined data from the final state after processing, e.g. the resulting local residual stresses, the current work provides real-time data from in situ experiments during laser surface hardening for the validation of temporal stress courses of numerical process simulations.

. Local and temporal strain and stress evolution is recorded by synchrotron X-ray diffraction during laser line hardening of SAE 4140 steel in the quenched and tempered states at different measuring positions with respect to the process zone. The in-situ diffraction experiments were performed at beamline P05@Petra III at DESY, Hamburg (Germany). The steel samples were line hardened using a 4 kW high-power diode laser (HPDL) unit at a constant laser feed of 800 mm/min. Using a specially designed process chamber that incorporates symmetrically attached fast silicon micro-strip line detectors, stress analysis using the sin² ψ -method in single-exposure mode, enabled measuring rates at 20 Hz. As a result of the temporal and spatial resolved analyses, the elastic strains were separated from the thermal strains.

A new technique is presented to overcome beam size limitation in full field imaging at high brilliance synchrotron sources using specially designed refractive X-ray optics. These optics defocus the incoming beam in vertical direction and reshape the intensity distribution from a Gaussian to a more desirable top-hat-shaped profile at the same time. With these optics X-ray full-field imaging of extended objects becomes possible without having to stack several scans or applying a cone beam geometry in order to image the entire specimen. For in situ experiments in general and for diffraction limited sources in particular this gain in field of view and the optimization of the intensity distribution is going to be very beneficial.

An in-situ X-ray diffraction investigation of a power controlled laser line hardening experiment has been carried out at the synchrotron beamline P05 at the German electron synchrotron (DESY) in Hamburg. During the process the local strain and stress evolution is monitored using synchrotron radiation with a time resolution of 10 Hz. Samples made of steel grade AISI 4140 were line hardened by means of a high-power diode laser (HPDL) unit at constant laser feed. A specially. designed process chamber was used, allowing the control of the inert gas atmosphere to avoid oxide scale formation. Through the symmetric application of 4 fast micro-strip line detectors various {hkl} - diffraction lines were recorded during the short-time heat treatment by means of the single exposure approach. Thermal and elastic strains were separated and time resolved stress analysis was carried out according to the sin(2)psi-method. Stress and strain evaluation during the complete laser hardening process lead to unprecedented experimental insights.

Recent advances in storage ring technology pioneered by MAX IV (Sweden) allow synchrotron radiation sources to achieve significantly smaller emittances than those currently in operation. This new, multi-bend achromat technology can thus boost spectral brightness, enabling unprecedented experimental possibilities. The high-energy synchrotron radiation facilities ESRF (France), SPring-8 (Japan), and APS (USA) have settled upgrade plans to improve their storage ring emittance by up to two orders of magnitude at 6 GeV electron energy. PETRA III at DESY has the largest circumference with 2.3 km. As the emittance scales favorably with the storage ring size, an upgrade of PETRA III offers the unique potential to reach a diffraction limit up to X-ray energies of 10 keV. Operating at 6 GeV with an emittance of 10 pmrad, this PETRA IV facility would pave the way for new experimental opportunities, especially for those using high photon energies.

Despite the fact that many efforts were directed into this direction in the past three decades, many problems cannot be properly addressed. The ultimate goal of regenerative medicine is the restoration of the original function of a tissue or an organ. This is clearly only partially achieved for cases like artificial joints, tooth restoration, or bone substitution. The current approaches are not biomimetic in the sense of this word.

The Imaging Beamline IBL/P05 at the DESY storage ring PETRA III, operated by the Helmholtz-Zentrum Geesthacht, has two dedicated endstations optimized for micro- and nanotomography experiments [1-3]. Here we present the status of the nanotomography endstation, highlight the latest instrumentation upgrades and present first experimental results. In particular in materials science, where structures with ceramics or metallic materials are of interest, X-ray energies of 15 keV and above are required even for sample sizes of several 10 μm in diameter. The P05 imaging beamline is dedicated to materials science and is designed to allow for imaging applications with X-ray energies of 10 to 50 keV. In addition to the full field X-ray microscopy setup, the layout of the nanotomography endstation allows switching to cone-beam configuration. Kinematics for X-ray optics like compound refractive lenses (CRLs), Fresnel zone plates (FZP) or beam-shaping optics are implemented and the installation of a Kirkpatrick Baez-mirror (KB mirror) system is foreseen at a later stage of the beamline development. Altogether this leads to a high flexibility of the nanotomography setup such that the instrument can be tailored to the specific experimental requirements of a range of sample systems.

Phase-contrast imaging has proven to be a valuable tool when investigating weak absorbing materials like soft tissue, due to its increased contrast compared to conventional absorption-contrast imaging. While propagation-based phase-contrast is an ideal tool to achieve highest resolution at a good contrast for almost not-absorbing material, it quickly comes to its limitations on applications demanding for a high dynamic range in contrast. For those applications grating-based phase-contrast is the tool of choice, although it lacks of spatial resolution compared to inline phase-contrast or attenuation-based microCT. To reduce this gap in spatial resolution we equipped the two PETRA III beamlines P05 and P07 with a customized set of mechanics to maximize the performance of the interferometer. After latest optimization steps our system allows for phase-contrast measurements in a continuous energy range between 10 keV and 80 keV . Dependent on investigated material and energy the setup is capable to achieve a spatial resolution of 5 μm on a field of view of 6.5 mm. We will present our implementation of grating-based phase-contrast computed tomography for fast and high-resolution measurements at the PETRA III along with its recent optimization, and demonstrate its performance based on different kinds of applications.

Synchrotron X-ray imaging is constantly achieving higher spatial resolution. In the field of grating-based phase- contrast imaging, these developments allow to directly resolve the interference patterns created by a phase grating without need for a analyzer grating. In this study we analyzed the performance of a single-grating interferometer and compared it to a conventional double-grating interferometer. Based on simulations and measurements of a test phantom we evaluated the sensitivity, resolution and signal to noise ratios of different setup configurations.

The Helmholtz-Zentrum Geesthacht operates the P05 Imaging Beamline at the DESY storage ring PETRA III. This beamline is dedicated to micro-and nanotomography with two endstations. This paper will present the nanotomography endstation layout and first results obtained from commissioning and test experiments.First tests have been performed with CRLs as X-ray objectives and newly developed rolled X-ray prism lenses as condenser optics. This setup allows a resolution of 100nm half period with an effective detector pixel size of 15nm. A first tomograph of a photonic glass sample was measured in early 2014.