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The I13 transmission X-ray microscope at Diamond Light Source (DLS) has been designed to cover a broad range of energies and field of views. The beamline operates on an undulator source, and a multilayer monochromator can be used to work at a larger bandwidth to enable faster acquisitions. The experimental design includes large working distances for the optics to allow installing in situ sample environments. This paper presents the current state of the experimental system and shows some of the latest results.

A simple and reliable way of characterizing double-sided hard X-ray Fresnel zone plates is presented. The measurements are performed in an X-ray tube-based setup where a near-monochromatic spectrum is isolated by differential measurements with a Cu and an Ni filter., Double-sided Fresnel zone plates are diffractive lenses used for high-resolution hard X-ray microscopy. The double-sided structures have significantly higher aspect ratios compared with single-sided components and hence enable more efficient imaging. The zone plates discussed in this paper are fabricated on each side of a thin support membrane, and the alignment of the zone plates with respect to each other is critical. Here, a simple and reliable way of quantifying misalignments by recording efficiency maps and measuring the absolute diffraction efficiency of the zone plates as a function of tilting angle in two directions is presented. The measurements are performed in a setup based on a tungsten-anode microfocus X-ray tube, providing an X-ray energy of 8.4 keV through differential measurements with a Cu and an Ni filter. This study investigates the sources of the misalignments and concludes that they can be avoided by decreasing the structure heights on both sides of the membrane and by pre-programming size differences between the front- and back-side zone plates.

The imaging of integrated circuits across different length scales is required for failure analysis, design validation and quality control. At present, such inspection is accomplished using a hierarchy of different probes, from optical microscopy on the millimetre length scale to electron microscopy on the nanometre scale. Here we show that ptychographic X-ray laminography can provide non-destructive, three-dimensional views of integrated circuits, yielding both images of an entire chip volume and high-resolution images of arbitrarily chosen subregions. We demonstrate the approach using chips produced with 16 nm fin field-effect transistor technology, achieving a reconstruction resolution of 18.9 nm, and compare our results with photolithographic mask layout files and more conventional imaging approaches such as scanning electron microscopy. The technique should also be applicable to other branches of science and engineering where three-dimensional X-ray images of planar samples are required. A technique that combines X-ray ptychography with laminography can provide three-dimensional views of integrated circuits, yielding both images of entire chip volumes and high-resolution images of arbitrarily chosen subregions, and is applicable to any imaging problem where the samples are planar.

International audience; Agile management of the optical orbital angular momentum encompasses temporal, spatial, and spectral aspects that, once combined, offer new perspectives in our way to manipulate light. To date the spectral control is mainly limited to tunable operating wavelength and polychromatic capabilities. Recently, a multispectral approach has been proposed [Phys. Rev. Lett. 121, 213901 (2018)] to achieve independent orbital angular momentum state control on multiple spectral channels. Here we report on the design, fabrication and implementation of a solid-state multispectral approach that consists of arrays of optical diamond micro-metasurfaces. Obtained device exhibits superior performances with respect to the original attempt, both regarding the spectral vortex purity, the ability to deal with high photon flux, and the orbital angular momentum diversity across the spectrum. These results motivate further development of metasurface-based integrated spin-orbit photonics technologies.

Diffraction gratings are key components in experiments with UV, VUV and soft x-ray radiation at synchrotron radiation and free-electron laser (FEL) facilities. They areused in monochromators to produce beams with narrow energy distribution, and in analyzers to provide high-resolution spectral analysis of scattered radiation. Today, such diffraction gratings consist of a large number of periodic grooves (typically tens to thousands per millimeter) arranged on the reflecting surface on a plane or concave substrate. The performance of the grating is also ultimately limited by the surface quality of the substrate. For best spectral resolution, the substrates need to be ultra-precise and superpolished, with typical lengths of 100 – 300 mm and shape errors of 1-2 nanometers, slope errors in the order of 100 nrad, and a roughness in the Angstrom scale. Today, the line patterns of x-ray gratings are mostly produced either by holographic exposures of interfering laser beams into a photo resist, or by ruling machines that imprint the grating groves in a line-by-line manner into a soft metal layer. As an alternative to these established methods, we present a strategy of grating fabrication by electron-beam lithography (EBL). This technique can expose arbitrary patterns with high resolution and placement accuracy at a speed sufficient for x-ray grating fabrication. We have performed optical metrology of a low-cost grating substrate, which served as the basis for an aligned exposure of a corrected grating pattern to yield a laminar grating with a constant deflection angle along the substrate surface. We have confirmed that the effects of slope errors were strongly compensated over an extended wavelength range by using synchrotron radiation in the soft x-ray range. This work shows a path for circumventing the limited availability of high quality reflective substrates to obtain gratings with performance beyond what is possible today.

At XRnanotech, a spin-off from the Paul Scherrer Institut (PSI) in Switzerland, we develop diffractive X-ray optics to enable experiments at many large-scale research facilities. Our goal is to push the limits of diffractive X-ray optics by continuously, improving the resolution and efficiency enabling new applications in microscopy to make the invisible visible. In X-ray microscopy, Fresnel zone plates (FZPs) are used as high-resolution lenses. Their resolution depends mainly on the size of their smallest outermost zones and many years of development were required in order to push this value into ever-smaller regimes. Recently, the 10 nm barrier was broken with the line-doubling approach. While the zone-doubling approach is very helpful for achieving ultra-high resolutions, it has a fundamental disadvantage compared to conventional FZPs in terms of efficiency. The efficiency of a FZP depends not only on the wavelength, the material and its optical thickness but also on the duty cycle. For a FZP consisting of structures with a continuously changing period along its radius, the duty cycle of the Ir structures changes accordingly, because the deposited Ir thickness by ALD is uniform. Consequently, the efficiency along the radius changes as a function of the duty cycle and drops to zero towards the center of the zone plate. An elegant method to mitigate this effect is to fabricate hybrid FZPs that consist of a conventional center region with structures made e.g. of gold by electroplating and a zone-doubled outer part, where the deviation in duty cycle is not as pronounced anymore. Here, by fabricating such a hybrid structure, we achieved 7 nm resolution in direct imaging with soft X-rays and are able to fabricate X-ray optics with ultra-high aspect ratios.

Applied physics letters 118(17), 171102 (1-5) (2021). doi:10.1063/5.0045571, Nondestructive imaging with both a large field of view and a high spatial resolution is crucial to understand complex materials and processes in science and technology. X-ray ptychography can provide highest spatial resolution but is limited in the field of view by the acquisition time and coherent flux at modern x-ray sources. By multi-beam ptychography, the sample can be imaged in parallel by several spatially separated and mutually incoherent beams. We have implemented this method using 3D nanoprinted x-ray optics to create tailor-made x-ray multi-beam arrays. The use of 3D printing allows us to create focusing optics with a minimum of nonfunctional support structures. In this way, large sample areas can be efficiently scanned in parallel with up to six illuminating beams., Published by American Inst. of Physics, Melville, NY

Optical-domain Transient Grating (TG) spectroscopy is a versatile background-free four-wave-mixing technique used to probe vibrational, magnetic and electronic degrees of freedom in the time domain. The newly developed coherent X-ray Free Electron Laser sources allow its extension to the X-ray regime. Xrays offer multiple advantages for TG: their large penetration depth allows probing the bulk properties of materials, their element-specificity can address core-excited states, and their short wavelengths create excitation gratings with unprecedented momentum transfer and spatial resolution. We demonstrate for the first time TG excitation in the hard X-ray range at 7.1 keV. In Bismuth Germanate (BGO), the nonresonant TG excitation generates coherent optical phonons detected as a function of time by diffraction of an optical probe pulse. This experiment demonstrates the ability to probe bulk properties of materials and paves the way for ultrafast coherent four-wave-mixing techniques using X-ray probes and involving nanoscale TG spatial periods., Comment: 11 pages, 4 figures

The characterization and commissioning of the X-ray photon single-shot spectrometer (PSSS) at the Aramis beamline of SwissFEL is presented. The device delivers online, non-invasive, high-resolution single-shot measurements of spectral profiles between 4 and 13 keV., The performance and parameters of the online photon single-shot spectrometer (PSSS) at the Aramis beamline of the SwissFEL free-electron laser are presented. The device operates between the photon energies 4 and 13 keV and uses diamond transmission gratings and bent Si crystals for spectral measurements on the first diffraction order of the beam. The device has an energy window of 0.7% of the median photon energy of the free-electron laser pulses and a spectral resolution (full width at half-maximum) ΔE/E on the order of 10−5. The device was characterized by comparing its performance with reference data from synchrotron sources, and a parametric study investigated other effects that could affect the reliability of the spectral information.

Beam splitters and delay lines are among the key building blocks of modern-day optical laser technologies. Progress in x-ray free electron laser source development and applications over the past decade is calling for their counter part operating in the Angstrom wavelength regime. Recent efforts in x-ray optics development have demonstrated relatively stable delay lines that most often adopted the division of wavefront approach for the beam splitting and recombination configuration. However, the two recombined beams have yet to achieve sufficient mutual coherence to enable applications such as interferometry, correlation spectroscopy, and nonlinear spectroscopy. We present the first experimental realization of the generation of highly mutually coherent pulse pairs using an amplitude-split delay line design based on transmission grating beam splitters and channel-cut crystal optic delay lines. The performance of the prototype system was analyzed in the context of x-ray coherent scattering and correlation spectroscopy, where we obtained nearly identical high-contrast speckle patterns from both branches. We show in addition the high level of dynamical stability during continuous delay scans, a capability essential for high sensitivity ultra-fast measurements., Comment: 16 pages, 9 gigures

Optics express 28(25), 37514-37525 (2020). doi:10.1364/OE.406074, X-ray phase contrast nanotomography enables imaging of a wide range of samples with high spatial resolution in 3D. Near-field holography, as one of the major phase contrast techniques, is often implemented using X-ray optics such as Kirkpatrick-Baez mirrors, waveguides and compound refractive lenses. However, these optics are often tailor-made for a specific beamline and challenging to implement and align. Here, we present a near-field holography setup based on Fresnel zone plates which is fast and easy to align and provides a smooth illumination and flat field. The imaging quality of different types of Fresnel zone plates is compared in terms of the flat-field quality, the achievable resolution and exposure efficiency i.e. the photons arriving at the detector. Overall, this setup is capable of imaging different types of samples at high spatial resolution of below 100 nm in 3D with access to the quantitative phase information., Published by Soc., Washington, DC

A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×10(17)W/cm(2) was obtained at 70 fs pulse length.

A new era of protein crystallography started when X-ray free-electron lasers (XFELs) came into operation, as these provide an intense source of X-rays that facilitates data collection in the `diffract-before-destroy' regime. In typical experiments, crystals sequentially delivered to the beam are exposed to X-rays and destroyed. Therefore, the novel approach of serial crystallography requires thousands of nearly identical samples. Currently applied sample-delivery methods, in particular liquid jets or drop-on-demand systems, suffer from significant sample consumption of the precious crystalline material. Direct protein microcrystal growth by the vapour diffusion technique inside arrays of nanolitre-sized wells is a method specifically tailored to crystallography at XFELs. The wells, with X-ray transparent Si3N4windows as bottoms, are fabricated in silicon chips. Their reduced dimensions can significantly decrease protein specimen consumption. Arrays provide crystalline samples positioned in an ordered way without the need to handle fragile crystals. The nucleation process inside these microfabricated cavities was optimized to provide high membrane coverage and a quasi-random crystal distribution. Tight sealing of the chips and protection of the crystals from dehydration were achieved, as confirmed by diffraction experiments at a protein crystallography beamline. Finally, the test samples were shown to be suitable for time-resolved measurements at an XFEL at femtosecond resolution.

Physical review / A covering atomic, molecular, and optical physics and quantum information 101(1), 013820 (2020). doi:10.1103/PhysRevA.101.013820, Here we present the results of a classical ghost imaging experiment accomplished at an XUV free-electronlaser (FEL). To perform such experiment at an FEL source each x-ray pulse was transmitted through a movingdiffuser, which created a noncorrelated speckled beam. This beam was then split in two identical branches byintroducing a beam splitter in the form of a transmission grating. In one of these branches the sample waspositioned. We demonstrate the possibility of image formation, a double bar in our case, in the beam that hasnever interacted with the sample. With this experiment we extend the quantum optics methodology to the FELcommunity., Published by Inst., Woodbury, NY

Journal of synchrotron radiation 27(5), 1121 - 1130 (2020). doi:10.1107/S1600577520007900, Modern subtractive and additive manufacturing techniques present new avenues for X-ray optics with complex shapes and patterns. Refractive phase plates acting as glasses for X-ray optics have been fabricated, and spherical aberration in refractive X-ray lenses made from beryllium has been successfully corrected. A diamond phase plate made by femtosecond laser ablation was found to improve the Strehl ratio of a lens stack with a numerical aperture (NA) of 0.88 × 10−3 at 8.2 keV from 0.1 to 0.7. A polymer phase plate made by additive printing achieved an increase in the Strehl ratio of a lens stack at 35 keV with NA of 0.18 × 10−3 from 0.15 to 0.89, demonstrating diffraction-limited nanofocusing at high X-ray energies., Published by Wiley-Blackwell, [S.l.]

Journal of synchrotron radiation 27(5), 1339 - 1346 (2020). doi:10.1107/S1600577520007407, Hard X-ray nanotomography enables 3D investigations of a wide range of samples with high resolution (, Published by Wiley-Blackwell, [S.l.]

X-ray Grating Talbot Interferometer (XGTI) is already routinely used for quantitative phase contrast imaging of soft tissue samples. XGTI can be realized using various measurement techniques, depending on the X-ray source used, the required spatial resolution and the speed of acquisition. The phase-stepping measurement technique, which is commonly used for XGTI data acquisition, needs multiple acquisitions for a single projection. For fast imaging the Moire technique, a single-shot technique, is often preferred. However, it requires two gratings which increases the dose on the sample. We have therefore examined the Spatial Harmonic Imaging (SHI) technique which is low-dose and single-shot, using the I13-2 Diamond-Manchester Beamline at Diamond Light Source (DLS). The DLS I13-2 beamline is equipped with a Double Crystal Monochromator (DCM) and a Multi-Layer Monochromator (MLM) to deliver monochromatic beam, which work at the energy bandwidths (ΔE/E) of 10-4 and 10-2, respectively. However, the disadvantage of using these monochromators, especially for fast imaging, is loss of X-ray flux. It has already been shown that XGTI can work with an energy bandwidth (ΔE/E) of 10-1. Our aim is to develop a single phase grating interferometer with pink beam from an undulator source, with X-ray mirror optics and multiple absorption filters, to obtain maximum possible flux with sufficient coherence and monochromaticity. We demonstrate performance with optimized beamline parameters for a photon energy of 15 keV with some demonstrative image reconstructions.

To date, compound refractive X-ray lenses made out of Beryllium (Be CRLs) have been seldom applied for full-field microscopy with high spatial resolution, which was probably due to residual aberrations of these optics. However, in combination with the recent development of made-to-measure phase plates, the typical spherical aberration of beryllium compound refractive lenses (Be CRLs) can now be completely removed. In this way, distortion-free images of a sample are obtained, which is especially important for tomographic applications. First full-field imaging experiments with aberration-corrected Be CRLs were carried out at beamline P06 at the synchrotron radiation X-ray source PETRA III (DESY Hamburg, Germany). In order to maximize the magnification of the X-ray microscope for full-field microscopy, the full length of the beamline combining the micro- and nanohutch was utilized, enabling a large sample-to-detector distance. In this contribution, we present first imaging results, demonstrating the potential of Be CRLs for direct high-resolution X-ray tomography.

The extension of transient grating spectroscopy to the x-ray regime will create numerous opportunities, ranging from the study of thermal transport in the ballistic regime to charge, spin, and energy transfer processes with atomic spatial and femtosecond temporal resolution. Studies involving complicated split-and-delay lines have not yet been successful in achieving this goal. Here we propose a novel, simple method based on the Talbot effect for converging beams, which can easily be implemented at current x-ray free electron lasers. We validate our proposal by analyzing printed interference patterns on polymethyl methacrylate and gold samples using similar to 3 keV X-ray pulses. (C) 2019 Optical Society of America

Optica 7(11), 1602 - 1608 (2020). doi:10.1364/OPTICA.399885, The availability of intense soft x-ray beams with tunable energy and polarization has pushed the development of highlysensitive, element-specific, and noninvasive microscopy techniques to investigate condensed matter with high spatialand temporal resolution. The short wavelengths of soft x-rays promise to reach spatial resolutions in the deep single-digitnanometer regime, providing unprecedented access to magnetic phenomena at fundamental length scales. Despiteconsiderable efforts in soft x-ray microscopy techniques, a two-dimensional resolution of 10 nm has not yet been surpassedin direct imaging. Here, we report on a significant step beyond this long-standing limit by combining newlydeveloped soft x-ray Fresnel zone plate lenses with advanced precision in scanning control and careful optical design.With this approach, we achieve an image resolution of 7 nm. By combining this highly precise microscopy techniquewith the x-ray magnetic circular dichroism effect,we reveal dimensionality effects in an ensemble of interacting magneticnanoparticles. Such effects are topical in current nanomagnetism research and highlight the opportunities of highresolutionsoft x-ray microscopy in magnetism research and beyond., Published by OSA, Washington, DC

X-ray free-electron lasers (XFELs) are paving the way towards new experiments in many scientific fields, such as ultrafast science, nonlinear spectroscopy, and coherent imaging. However, the strong intensity fluctuations inherent to the lasing process in these sources often lead to problems in signal normalization. In order to address this challenge, we designed, fabricated, and characterized diffractive x-ray optics that combine the focusing properties of a Fresnel zone plate with the beam-splitting capability of a grating in a single diffractive optical element. The possibility to split the incident beam into identical copies allows for direct shot-to-shot normalization of the sample signal, thereby greatly enhancing the signal-to-noise ratio in experiments with XFEL radiation. Here we propose two schemes for the design of such diffractive x-ray optical elements for splitting and focusing an incoming beam into up to three foci by merging a grating with a focusing zone plate. By varying the duty cycle of the grating or the relative shift of the Fresnel zone plate structure, we are able to tune the relative intensities of the different diffraction orders to achieve the desired splitting ratios. Experimental confirmation of the design is provided with soft x-ray light (540 eV) and shows a good agreement with calculations, confirming the suitability of this approach for XFEL experiments.

Journal of synchrotron radiation 26(2), 467 - 472 (2019). doi:10.1107/S1600577519000869, This article reports on the fabrication and testing of dedicated Fresnel zone plates for use at the nano-ARPES branch of the I05-ARPES beamline of Diamond Light Source to perform angle-resolved photoelectron spectroscopy with sub-micrometre resolution in real space. The aim of the design was to provide high photon flux combined with sub-micrometre spot sizes. The focusing lenses were tested with respect to efficiency and spatial resolution in the extreme ultraviolet between 50 eV and 90 eV. The experimentally determined diffraction efficiencies of the zone plates are as high as 8.6% at 80 eV, and a real-space resolution of 0.4 µm was demonstrated. Using the zone-plate-based setup, monolayer flakes of the two-dimensional semiconductor WS2 were investigated. This work demonstrates that the local electronic structure can be obtained from an area of a few micrometres across a two-dimensional heterostructure., Published by Wiley-Blackwell, [S.l.]

The advancements in bright and coherent X-ray free-electron lasers (XFEL) have in the last decade revolutionized diverse fields of study, leading to an ever-increasing demand in more intense X-ray pulses. The accurate knowledge of the wavefront and the focal profile of such pulses ultimately dictates much of the experimental outcome. Here we present a single-shot shearing interferometry method to measure the wavefront of a focused hard XFEL pulse. Two identical transmission gratings are placed near the focus, and the interference pattern of overlapping diffraction orders is analyzed, resulting in a two-dimensional reconstruction of the X-ray wavefront. The spatial resolution and wavefront sensitivity can be tuned in-situ during the measurement. The method is non-invasive (i.e., the zeroth order or transmitted pulse is not modified in intensity or profile), allowing for either a simultaneous intensity measurement at high resolution or a fully characterized transmitted pulse for general experimental use.

The European X-ray Free Electron Laser (EuXFEL) offers intense, coherent femtosecond pulses, resulting in characteristic peak brilliance values a billion times higher than that of conventional synchrotron facilities. Such pulses result in extreme peak radiation levels of the order of terawatts cm−2 for any optical component in the beam and can exceed the ablation threshold of many materials. Diamond is considered the optimal material for such applications due to its high thermal conductivity (2052 W mK−1 at 300 K) and low absorption for hard X-rays. Grating structures were fabricated on free-standing CVD diamond of 10 µm thickness with 500 µm silicon substrate support. The grating structures were produced by electron-beam lithography at the Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, Switzerland. The grating lines were etched to a depth of 1.2 µm, resulting in an aspect ratio of 16. The characterization measurements with X-rays were performed on transmissive diamond gratings of 150 nm pitch at the P10 beamline of PETRA III, DESY. In this paper, the gratings are briefly described, and a measured diffraction efficiency of 0.75% at 6 keV in the first-order diffraction is shown; the variation of the diffraction efficiency across the grating surface is presented.

New X-ray imaging techniques are currently being developed at the "Commissariat a l'energie atomique et aux energies alternatives" in the context of Inertial Confinement Fusion. Fresnel zone plates (FZPs) are being considered as they can perform high-resolution and high-flux imaging in the X-ray domain. Here we present the characterization of a bi-lens FZPs resolution used in an imager prototype, designed for the LULI2000 laser facility. Characterization was performed on a synchrotron radiation facility and on a femtosecond laser facility. The resolution of the two FZP channels was measured to be between 2.4 μm and 5.2 μm and the expected total resolution for the diagnostic was to be 3.3 μm.

Preserving the coherence and wavefront of a diffraction limited x-ray beam from the source to the experiment poses stringent quality requirements on the production processes for X-ray optics. In the near future this will require on-line and in-situ at-wavelength metrology for both, free electron lasers and diffraction limited storage rings. A compact and easy to move X-ray grating interferometry (XGI) setup has been implemented by the Beamline Optics Group at PSI in order to characterize x-ray optical components by determining the aberrations from reconstructing the x-ray wavefront. The XGI setup was configured for measurements in the moire mode and tested with focusing optic at Swiss Light Source, Diamond Light Source and LCLS. In this paper measurements on a bendable toroidal mirror, a zone plate, a single and a stack of beryllium compound refractive lenses (CRL) are presented. From these measurements the focal position and quality of the beam spot in terms of wavefront distortions are determined by analysing the phase-signal obtained from the XGI measurement. In addition, using a bendable toroidal mirror, we directly compare radius of curvature measurements obtained from XGI data with data from a long-trace profilometer, and compare the CRL wavefront distortions with data obtained by ptychography.

The Diamond I13 imaging and coherence beamline performs multiscale imaging and tomography with phase sensitive imaging methods. Operating in the energy range of 6-30keV, the achievable resolution ranges from several microns to tens of nanometers [1,2]. The beamline is unique in combining imaging methods in real and reciprocal spaces, which are available on two independently operating branchlines. The scientific program is currently being developed with the distinct capabilities offered by the beamline. Most recently ptycho-tomography has become operational and a multitude of scientific projects is linking the research between both branchlines. The Diamond-Manchester imaging branchline performs mainly in-line phase contrast microtomography with a strong emphasis on dedicated sample environments. Failure of lithium batteries, material cracks, structure of ice cream, bones under load, and storage of CO2 in brine and sandstone are some examples studied under realistic conditions. Most experiments are carried out in the so-called polychromatic 'pink-beam' mode, with micron resolution and millisecond exposure times. Furthermore, a multilayer and a Si (111) monochromator are available for element selective measurements. Two additional projects (full-field microscope and grating interferometry) are currently under development for studies with submicron resolution and phase sensitive imaging. The full-field microscope can perform Zernike phase contrast imaging over a field of view of 50-100µm with a resolution of 50-100nm. The large working distance over several centimeters enable a large variety of scientific applications with dedicated sample environments [3,4]. The different stripes of the multilayer monochromator provide a bandwidth between E/E=10-3 and 10-2 and combined with a fibre-optic plate coupled sCMOS detector, exposure times of few 100ms are achieved. Grating interferometry provides superb image quality, measuring the absolute phase and providing small angle information. We currently plan to apply this method to identify nano-sized structures with micrometer resolution [5,6], as for example in the studies on bones, battery materials, pharmaceutical products or industrial filter materials. Highest spatial resolution is achieved on the coherence branch with ptychographic imaging with 30nm spatial resolution. The photon counting EXCALIBUR detector can continuously record with a speed of up to 250Hz over an array of 1.5x2kPixels. After the last year of development the recording speed for ptycho-tomography scan has significantly improved. A full scan currently takes a few hours and is anticipated to be further accelerated. Ptychography is now performed as standard user experiment, enabling the beamline's ambition for multi-scale imaging. A large number of pilot experiments are being

International audience; We report on indirect X-ray detector systems for various full-field, ultra high-speed X-ray imaging methodologies, such as X-ray phase-contrast radiography, diffraction topography, grating interferometry and speckle-based imaging performed at the hard X-ray imaging beamline ID19 of the European Synchrotron—ESRF. Our work highlights the versatility of indirect X-ray detectors to multiple goals such as single synchrotron pulse isolation, multiple-frame recording up to millions frames per second, high efficiency, and high spatial resolution. Besides the technical advancements, potential applications are briefly introduced and discussed.

The development of X-ray free-electron lasers (XFELs) has opened the possibility to investigate the ultrafast dynamics of biomacromolecules using X-ray diffraction. Whereas an increasing number of structures solved by means of serial femtosecond crystallography at XFELs is available, the effect of radiation damage on protein crystals during ultrafast exposures has remained an open question. We used a splitand-delay line based on diffractive X-ray optics at the Linac Coherent Light Source XFEL to investigate the time dependence of X-ray radiation damage to lysozyme crystals. For these tests, crystals were delivered to the X-ray beam using a fixed-target approach. The presented experiments provide probe signals at eight different delay times between 19 and 213 femtoseconds after a single pump event, thereby covering the time-scales relevant for femtosecond serial crystallography. Even though significant impact on the crystals was observed at long time scales after exposure with a single X-ray pulse, the collected diffraction data did not show significant signal reduction that could be assigned to beam damage on the crystals in the sampled time window and resolution range. This observation is in agreement with estimations of the applied radiation dose, which in our experiment was clearly below the values expected to cause damage on the femtosecond time scale. The experiments presented here demonstrate the feasibility of time-resolved pump-multiprobe X-ray diffraction experiments on protein crystals. (C) 2018 Author(s).

Ultrafast dynamics are generally investigated using stroboscopic pump-probe measurements, which characterize the sample properties for a single, specific time delay. These measurements are then repeated for a series of discrete time delays to reconstruct the overall time trace of the process. As a consequence, this approach is limited to the investigation of fully reversible phenomena. We recently introduced an off-axis zone plate based X-ray streaking technique, which overcomes this limitation by sampling the relaxation dynamics with a single femtosecond X-ray pulse streaked over a picosecond long time window. In this article we show that the X-ray absorption cross section can be employed as the contrast mechanism in this novel technique. We show that changes of the absorption cross section on the percent level can be resolved with this method. To this end we measure the ultrafast magnetization dynamics in CoDy alloy films. Investigating different chemical compositions and infrared pump fluences, we demonstrate the routine applicability of this technique. Probing in transmission the average magnetization dynamics of the entire film, our experimental findings indicate that the demagnetization time is independent of the specific infrared laser pump fluence. These results pave the way for the investigation of irreversible phenomena in a wide variety of scientific areas., Comment: 9 pages, 5 figures

14th International Conference on X-ray Microscopy, XRM2018, Saskatoon, Canada, 19 Aug 2018 - 24 Aug 2018; Microscopy and microanalysis 24(S2), 186 - 187 (2018). doi:10.1017/S1431927618013284, Published by Cambridge University Press, New York, NY

The generation of low-emittance electron beams has received significant interest in recent years. Driven by the requirements of X-ray-free electron lasers, the emittance of photocathode injectors has been reduced significantly, with corresponding increase in beam brightness. This has put increasingly stringent requirements on the instrumentation to measure the beam size. These requirements are even more stringent for novel accelerator developments, such as laser-driven accelerators based on dielectric structures or on a plasma. We present here the generation and measurement of a sub-micrometer electron beam, at a particle energy of 330 MeV, and a bunch charge below 1 pC. An electron-beam optics with a vertical β-function of a few millimeters has been setup. The beam is characterized through a wire scanner that employs a 1 μm wide metallic structure fabricated using the electron-beam lithography. The smallest (rms) transverse beam size presented here is

Here we present results stemming from the first prototype of the Neutron Microscope instrument at Paul ScherrerInstitut (PSI). The instrument is based on a very thin gadolinium oxysulfide (Gd2O2S:Tb+) scintillator screen and a magnifying optics. The Neutron Microscope prototype has been tested at the ICON and the BOA beamlines at PSI and sub-10 μm features can be clearly resolved on a focussed ion beam (FIB) enhance test object – a gadolinium-based Siemens star. The spatial resolution of the images of the gadolinium-based Siemensstar assessed by Fourier ring correlation was about 7.6 μm. The outlook for future improvement of the Neutron Microscope system is presented.

Scientific reports 7(1), 7253(2017). doi:10.1038/s41598-017-07069-z, The advent of x-ray free electron lasers has extended the unique capabilities of resonant x-ray spectroscopy techniques to ultrafast time scales. Here, we report on a novel experimental method that allows retrieving with a single x-ray pulse the time evolution of an ultrafast process, not only at a few discrete time delays, but continuously over an extended time window. We used a single x-ray pulse to resolve the laser-induced ultrafast demagnetisation dynamics in a thin cobalt film over a time window of about 1.6 ps with an excellent signal to noise ratio. From one representative single shot measurement we extract a spin relaxation time of (130 ± 30) fs with an average value, based on 193 single shot events of (113 ± 20) fs. These results are limited by the achieved experimental time resolution of 120 fs, and both values are in excellent agreement with previous results and theoretical modelling. More generally, this new experimental approach to ultrafast x-ray spectroscopy paves the way to the study of non-repetitive processes that cannot be investigated using traditional repetitive pump-probe schemes., Published by Macmillan, London

Multi-keV X-ray microscopy has been particularly successful in bridging the resolution gap between optical and electron microscopy. However, resolutions below 20 nm are still considered challenging, as high throughput direct imaging methods are limited by the availability of suitable optical elements. In order to bridge this gap, we present a new type of Fresnel zone plate lenses aimed at the sub-20 and the sub-10 nm resolution range. By extending the concept of double-sided zone plate stacking, we demonstrate the doubling of the effective line density and thus the resolution and provide large aperture, singlechip optical devices with 15 and 7 nm smallest zone widths. The detailed characterization of these lenses shows excellent optical properties with focal spots down to 7.8 nm. Beyond wave front characterization, the zone plates also excel in typical imaging scenarios, verifying their resolution close to their diffraction limited optical performance., published version, peerReviewed

High-efficiency nanofocusing of hard X-rays using stacked multilevel Fresnel zone plates with a smallest zone width of 200 nm is demonstrated. The approach is to approximate the ideal parabolic lens profile with two-, three-, four- and six-level zone plates. By stacking binary and three-level zone plates with an additional binary zone plate, the number of levels in the optical transmission function was doubled, resulting in four- and six-level profiles, respectively. Efficiencies up to 53.7% focusing were experimentally obtained with 6.5 keV photons using a compact alignment apparatus based on piezoelectric actuators. The measurements have also been compared with numerical simulations to study the misalignment of the two zone plates.

Wavefront preservation of reflective X-ray optics, i.e., homogeneity and coherence properties of the reflected beam, are of crucial importance for their application in combination with high-brilliance synchrotron light sources. In order to compare the performance of optical elements in a quantitative manner, a protocol has been established using the Talbot effect to access the coherence properties of the reflective beam as well as long propagation distance imaging to study its homogeneity. The basic idea is to operate in a single-bounce geometry: a high-resolution imaging detector translated at short propagation distances along the beam is used to measure the visibility of a diffraction grating in transmission geometry placed close to the mirror under study. The change of the fringe visibility as a function of distance between the grating and the detector gives access to the angular source size. A second high-resolution imaging detector at longer propagation distances of up to several meters allows one to measure the homogeneity of the beam. This article outlines the concept as realized at beamline ID19 of the European Synchrotron Radiation Facility, gives insight into some of the technical details to be considered for implementation at other facilities and ends with an example application: the study of a W / B 4 C multilayer mirror.

A two-dimensional (2D) grating interferometer was used to perform at-wavelength metrology. A Fast Fourier Transform (FFT) of the interferograms recovers the differential X-ray beam phase in two orthogonal directions simultaneously. As an example, the X-ray wavefronts downstream from a Fresnel Zone plate were measured using the moire fringe analysis method, which requires only a single image. The rotating shearing interferometer technique for moire fringe analysis was extended from one dimension to two dimensions to carry out absolute wavefront metrology. In addition, the 2D moire fringes were extrapolated using Gerchberg's method to reduce the boundary artifacts. The advantages and limitations of the phase-stepping method and the moire fringe analysis method are also discussed.

An efficient computing simulation routine has been implemented to model explicitly several types of Fresnel zone plate taking advantage of the circular symmetry. This code was used to evaluate an optimized approach for stacking of two high-resolution Fresnel zone plates., A computing simulation routine to model any type of circularly symmetric diffractive X-ray element has been implemented. The wavefield transmitted beyond the diffractive structures is numerically computed by the angular spectrum propagation method to an arbitrary propagation distance. Cylindrical symmetry is exploited to reduce the computation and memory requirements while preserving the accuracy of the numerical calculation through a quasi-discrete Hankel transform algorithm, an approach described by Guizar-Sicairos & Gutierrez-Vega [J. Opt. Soc. Am. A, (2004 ▶), 21, 53–58]. In particular, the code has been used to investigate the requirements for the stacking of two high-resolution Fresnel zone plates with an outermost zone width of 20 nm.

Deformation of the first crystal of an X-ray monochromator under the heat load of a high-power beam, commonly referred to as `heat bump', is a challenge frequently faced at synchrotron beamlines. Here, quantitative measurements of the deformations of an externally water-cooled silicon (111) double-crystal monochromator tuned to a photon energy of 17.6 keV are reported. These measurements were made using two-dimensional hard X-ray grating interferometry, a technique that enables in situ at-wavelength wavefront investigations with high angular sensitivity. The observed crystal deformations were of the order of 100 nm in the meridional and 5 nm in the sagittal direction, which lead to wavefront slope errors of up to 4 µrad in the meridional and a few hundred nanoradians in the sagittal direction.

The high-throughput 3D visualisation of biological specimens is essential for studying diseases and developmental disorders. It requires imaging methods that deliver high-contrast, high-resolution volumetric information at short sample preparation and acquisition times. Here we show that X-ray phase-contrast tomography using a single grating can provide a powerful alternative to commonly employed techniques, such as high-resolution episcopic microscopy (HREM). We present the phase tomography of a mouse embryo in paraffin obtained with an X-ray single-grating interferometer at I13-2 Beamline at Diamond Light Source and discuss the results in comparison with HREM measurements. The excellent contrast and quantitative density information achieved non-destructively and without staining using a simple, robust setup make X-ray single-grating interferometry an optimum candidate for high-throughput imaging of biological specimens as an alternative for existing methods like HREM.