This PDF file contains the front matter associated with SPIE Proceedings Volume 11839 including the Title Page, Copyright information, and Table of Contents.

X-ray microscopy is an invaluable and powerful characterization tool applied in many scientific fields, such as materials science, biology, environmental science, and energy research. In recent years it has been driven by rapid developments of novel technologies and systems resulting in imaging experiments elucidating structural inhomogeneities and chemical reactions at the nanometer scale. To obtain high spatial resolution comprehensive chemical and structural information, an X-ray microscope must be equipped with adequate capabilities and allow for simultaneous acquisition of multiple datasets. In recent years, a number of X-ray microscopes have been designed, constructed, and commissioned at NSLS-II. Here we provide an overview of the microscopy instrumentation development program at NSLS-II and specifically focus on the multilayer Laue lens–based hard X-ray nanoprobe optimized for ~10 nm spatial resolution imaging, its current status, and future upgrades along with recently constructed Kirkpatrick-Baez based scanning microscope designed for ~100 nm spatial resolution experiments.

Synchrotron scanning X-ray microscopy has been established as a mature technique, bridging the gap between conventional optical microscopy and high-resolution electron microscopy and, notably, adding advantages like large penetration in bulky samples, dose reduction and spectroscopy. The CARNAÚBA beamline at the 4th generation synchrotron source Sirius-LNLS provides an X-ray nanoprobe for simultaneous multi-analytical and coherent X-ray imaging techniques, with spectroscopic capabilities in the 2.05 to 15 keV energy range. The sample is raster-scanned through the nanoprobe to provide two-dimensional maps, which can then be combined with a rotation for computed tomography. In this contribution, some relevant scientific cases for the Day-1 experiments will be presented, along with original instrument solutions for in situ, in operando, cryogenic and in vivo sample environments.

We will present the design for the In-Situ Nanoprobe (ISN) beamline that is being developed as part of the Upgrade of the APS storage ring with an MBA magnetic lattice. The ISN will provide large working distance of 60 mm for in-situ and operando environments, and a small spot of 20 nm (25 keV) for imaging materials with small defects and functional components. To achieve both long working distance and small spot size, Kirkpatrick-Baez mirrors will be used as nanofocusing optics. The major contrast mechanisms will be XRF imaging for chemical characterization ptychography for transmission imaging with sub-10 nm resolution. Auxiliary diffraction capabilities will allow monitoring of phase change during in-situ studies. To achieve the demagnification required to achieve small spot sizes, the ISN instrument will be placed at a distance of 220 m from the x-ray source, in a satellite building outside the APS storage ring. The ISN will provide hard x-rays with photon energy between 4.8 keV and 30 keV, enabling access to the absorption edges of to most elements in the periodic system. The MBA lattice and insertion devices, coupled with the high reflectivity of the K-B mirror system, provide a very high coherent flux of above 4*10¹² Ph/s at 5 keV, and 6*10¹² Ph/s at 30 keV. This allows hierarchical imaging of large samples with very small spot size, as well as multidimensional imaging, such as 3D imaging and temperature change, or 2D imaging with change of several environmental parameters. The ISN will provide flow of fluids, gases, and variable temperature.

We report about our current capabilities and future plans in multi-scale imaging with high recording speed. For micro-tomographic imaging an automated system is used measuring up to 300 samples per day. For sub-micron and nano measurements the so-called polychromatic ‘pink beam’ is employed. The larger energy bandwidth compared to monochromatic beam permits recording times similar to microtomography. For highest resolution namely ptychography the acquisition time for tomographic scans is currently in the order of hours and below an hour in the near future. The current multi-scale science and the scientific perspective with the Diamond beamline I13L upgrade will be presented.

Time resolved x-ray microscopy allows researchers to investigate variation of the electronic structure of a material during chemical, structural or magnetic changes with picosecond time resolution. In this talk we will show how such a microscope can be realized using a field programming gate array in combination with a fast point detector. We will show results based on an existing setup, e.g. movies of spin waves in confined magnetic structures with a periodicity of a few ns, but also describe how this method can be extended to dynamical processes with longer observation times using state of the art FPGA technology. Time resolved measurements with high spatial resolution will be an important part of research at future x-ray sources like e.g. ALS-U.

Many questions regarding dynamic materials could be answered by using time-resolved ultra-fast imaging techniques to characterize the physical and chemical behavior of materials in extreme conditions and their evolution on the nanosecond scale. In this work, we perform multi-frame phase-contrast imaging (PCI) of micro-voids in low density polymers under laser-driven shock compression. At the Matter in Extreme Conditions (MEC) Instrument at the Linac Coherent Light Source (LCLS), we used a train of four x-ray free electron laser (XFEL) pulses to probe the evolution of the samples. To visualize the void and shock wave interaction, we deployed the Icarus V2 detector to record up to four XFEL pulses, separated by 1-3 nanoseconds. In this work, we image elastic waves interacting with the micro-voids at a pressure of several GPa. Monitoring how the material’s heterogeneities, like micro-voids, dictate its response to a compressive wave is important for benchmarking the performances of inertial confinement fusion energy materials. For the first time in a single sample, we have combined an ultrafast x-ray framing camera and four XFEL pulse train to create an ultrafast movie of micro-void evolution under laser-driven shock compression. Eventually, we hope this technique will resolve the material density as it evolves dynamically under laser shock compression.

A wavefront measurement method in the microscope (magnifying) geometry can help achieve the required high accuracy for deformable mirrors. This study proposes an image-based wavefront measurement method based on a series of images of a small area near the focus. In this method, phase retrieval calculation using multiple images is performed. A proof-of-concept experiment was performed using multilayer AKB mirrors and an FZP to form the small area. Consequently, wavefront aberration was successfully retrieved using 60 images of a 30-nm-diameter area near the focus.

A possible improvement on a new method of single acquisition hyperspectral (spectroscopic) ptychographic imaging, making use of a hyperspectral X-ray camera, is presented. Undulator tapering is used at the synchrotron to broaden the energy distribution of the X-ray beam to a suitable level for edge subtraction. The combination of a coherent imaging method such as ptychography with spectroscopy poses difficulties in experimental setup design regarding probe size. The final goal of the experiment, a K-edge subtraction, is not successful, but the technique is nevertheless promising. The capability of resolving the absorption edge applies to a wide range of research areas, such as element specific investigations in biological, materials, and earth sciences. We discuss the problems and their possible solutions.

Here we present soft X-ray linear dichroic ptychography developed at the COherent Scattering and MICroscopy (COSMIC) beamline at the Advanced Light Source (ALS) by studying biominerals—complex 3D hierarchically structured mineral-organic composite materials—produced by living organisms. Sequences of soft x-ray ptychography images at varying EPU polarizations were acquired, which principally allows visualization and orientation mapping of complex biogenic ultrastructures with spatial resolution down to 8 nm. These correlative data not only shed light on key mechanisms of the formation and mechanical principles of these composites but also demonstrate the capabilities and limitations of this newly developed technique, such as orientational precision, angular resolution and thickness related restrictions.

Ptychography has become a popular technique for high-throughput and high-resolution characterization of 2D/3D materials. When objects introduce significantly large phase shifts, a multi-slice model needs to be considered to account for long-distance wave propagation within the sample. Although many groups have demonstrated multi-slice ptychography using specimens that are several times larger than the depth of field (DOF), the benefits of applying the multi-slice ptychography algorithm on small objects within the DOF is rarely discussed. Here we address this question and demonstrate that multi-slice ptychography can play an important role in improving reconstruction quality for continuous objects that are smaller than the DOF.

X-ray ptychography imaging at synchrotron facilities like the Advanced Photon Source (APS) involves controlling instrument hardwares to collect a set of diffraction patterns from overlapping coherent illumination spots on extended samples, managing data storage, reconstructing ptychographic images from acquired diffraction patterns, and providing the visualization of results and feedback. In addition to the complicated workflow, ptychography instrument could produce up to several TB’s of data per second that is needed to be processed in real time. This brings up the need to develop a high performance, robust and user friendly processing software package for ptychographic data analysis. In this paper we present a software framework which provides functionality of visualization, work flow control, and data reconstruction. To accelerate the computation and large datasets process, the data reconstruction part is implemented with three algorithms, ePIE,¹ DM² and LSQML³ using CUDA-C on GPU.

For a long time in computed tomography (CT), noise and missing wedge have been two significant issues prohibiting researchers from obtaining reliable insights into material's intrinsic structures. Though much work has been done to denoise sinograms or recover the missing information, from traditional algorithms to emerging machine learning (ML) methods, most of them focus on perceptual performance, i.e., better visual consistency of data. This metric is adequate for computer vision applications, yet is insufficient for the scientific community where data fidelity is more critical, e.g., in the medical fields. In this work, we are trying to combine ML methods and the inherent properties of sinograms, aiming to achieve both state-of-the-art perceptual performance and high fidelity of the filled data. Distinguished from existing ML architectures, we propose a two-fold model implemented through neural networks: one using generative adversarial networks (GAN) and autoencoder to denoise/inpaint the missing-wedge sinogram, and the other one using convolutional neural networks (CNN) model to enforce the denoised/inpainted sinogram to obey their inherent properties. These two steps may need iterate to achieve consistent results. The results on both simulated and experimental data have demonstrated that our methods have achieved state-of-the-art perceptual performance and high fidelity. Our work further indicates that it is possible to incorporate physics into scientific ML models to make ML models more robust and accurate, significantly benefiting the scientific research aided by ML methods. This work is supported by the LDRD program at the FXI facility at NSLS-II, Brookhaven National Laboratory (BNL).

As X-ray imaging is pushed further into the nanoscale, the sample deformations due to the increased radiation levels or mechanical instabilities of the microscopes become more apparent, leading to challenges in realizing high-resolution microscopy under these conditions. Here we propose a distributed optimization solver for imaging of samples at the nanoscale. Our approach solves the tomography and ptychography problems jointly with projection data alignment, nonrigid sample deformation correction, and regularization. Applicability of the method is demonstrated on experimental data sets from the Transmission X-ray Microscope, and the hard X-ray nanoprobe.

Recently we demonstrated the phase-sensitive X-ray imaging technique based on the bilens interferometer. The essence of the method consisted of scanning a sample, which was set upstream of the bilens across the beam of one lens of the bilens, and recording changes in the interference pattern. This optical scheme involves fine-tuning the position of the sample on the optical axis, while a small deviation can lead to some distortion of its reconstructed phase profile. In this work, the advanced optical layout is considered. Knowing that the bilens generate two diffraction-limited focal spots, the sample can be placed in the focal plane of the bilens CRLs. In this case, the small size of the focused beams provides excellent phase sensitivity and high spatial resolution allowing to avoid possible distortions of the phase profile completely. The capabilities of both optical schemes were studied theoretically and experimentally.

Spectromicroscopy techniques allow the study of local chemical states along with morphology information. At the hard X-ray nanoprobe (HXN) beamline at NSLS-II, we developed nanoscale chemical imaging with high chemical state sensitivity and micron-scale penetration depth. In addition to the chemical images, XRF and phase-contrast images collected simultaneously offer multi-modal, correlative image analysis. We also developed a highly interactive, python-based graphical user interface (NSLS-II MIDAS) that allows multi-modal analysis of nano-XANES and XRF images. Advanced supervised and unsupervised learning algorithms enable users to explore the traditional XANES analysis along with standard machine-learning tools

We have developed precision mirror-based hard X-ray optics for focusing XFEL to less than 50nm at SACLA and for full-field imaging at SPring-8, in both of which we have realized diffraction-limited characteristics. I will talk about these achievements together with the latest status and future prospects.

The generation of single isolated attosecond pulses in the extreme ultraviolet (XUV) together with fully synchronized few-cycle infrared (IR) laser pulses allowed to trace electronic processes on the attosecond timescales. A pump/probe technique (attsecond streaking) was used to investigate electron dynamics on surfaces and layered systems with unprecedented resolution. We were able to measure the absolute emission time of electrons upon the photoelectric effect, delays in photoemission of electrons of different species, energy-dependant delays, the influence of the band-structure or wavepacket properties on the emission time in various materials and layered systems.

Dynamic X-ray detectors at the National Ignition Facility play a crucial role on High-Energy-Density (HED) experiments. They record data in the form of X-ray spectra, hot spot emission profiles, radiographic images, et cetera. The fast (pico- to nanoseconds) time scales and harsh environments of the HED experiments at the NIF impose tight constraints on the performance of these instruments, both in terms of temporal and spatial resolution, background rejection as well as their survivability. We are constantly striving to improve the quality of the data collected by identifying, implementing, and integrating cutting-edge technology, such as the hybridized CMOS cameras from SNL [1]. Here we provide a summary of the how we utilize these multi-frame nanosecond cameras in our X-ray detectors for HED experiments.