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Broadband X-ray ptychography is developed based on the multi-wavelength reconstruction method and is systematically demonstrated in both simulation and experiment. In addition, a combined reconstruction approach is proposed to further increase the ptychographic imaging rate., Ptychography is a rapidly developing scanning microscopy which is able to view the internal structures of samples at a high resolution beyond the illumination size. The achieved spatial resolution is theoretically dose-limited. A broadband source can provide much higher flux compared with a monochromatic source; however, it conflicts with the necessary coherence requirements of this coherent diffraction imaging technique. In this paper, a multi-wavelength reconstruction algorithm has been developed to deal with the broad bandwidth in ptychography. Compared with the latest development of mixed-state reconstruction approach, this multi-wavelength approach is more accurate in the physical model, and also considers the spot size variation as a function of energy due to the chromatic focusing optics. Therefore, this method has been proved in both simulation and experiment to significantly improve the reconstruction when the source bandwidth, illumination size and scan step size increase. It is worth mentioning that the accurate and detailed information of the energy spectrum for the incident beam is not required in advance for the proposed method. Further, we combine multi-wavelength and mixed-state approaches to jointly solve temporal and spatial partial coherence in ptychography so that it can handle various disadvantageous experimental effects. The significant relaxation in coherence requirements by our approaches allows the use of high-flux broadband X-ray sources for high-efficient and high-resolution ptychographic imaging.

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.

As a coherent diffraction imaging technique, ptychography provides high-spatial resolution beyond Rayleigh’s criterion of the focusing optics, but it is also sensitively affected by the decoherence coming from the spatial and temporal variations in the experiment. Here we show that high-speed ptychographic data acquisition with short exposure can effectively reduce the impact from experimental variations. To reach a cumulative dose required for a given resolution, we further demonstrate that a continuous multi-pass scan via high-speed ptychography can achieve high-resolution imaging. This low-dose scan strategy is shown to be more dose-efficient, and has potential for radiation-sensitive sample studies and time-resolved imaging.

X-ray ptychography has gained tremendous success in providing quantitative high-resolution imaging for extended samples. Here we report on recent developments in ptychography imaging techniques and the improvement of reconstruction methods to increase ptychographic imaging throughput at the Advanced Photon Source.

X-ray ptychography is a rapidly developing coherent diffraction imaging technique that provides nanoscale resolution on extended field-of-view. However, the requirement of coherence and the scanning mechanism limit the throughput of ptychographic imaging. In this paper, we propose X-ray ptychography using multiple illuminations instead of single illumination in conventional ptychography. Multiple locations of the sample are simultaneously imaged by spatially separated X-ray beams, therefore, the obtained field-of-view in one scan can be enlarged by a factor equal to the number of illuminations. We have demonstrated this technique experimentally using two X-ray beams focused by a house-made Fresnel zone plate array. Two areas of the object and corresponding double illuminations were successfully reconstructed from diffraction patterns acquired in one scan, with image quality similar with those obtained by conventional single-beam ptychography in sequence. Multi-beam ptychography approach increases the imaging speed, providing an efficient way for high-resolution imaging of large extended specimens.

Electric vehicles (EVs) can be utilized as mobile storages in a power system. The use of battery chargers can cause current harmonics in the supplied AC system. In order to analyze the impact of different EVs with regardto their number and their emission of current harmonics, a generic harmonic current model of EV types was built and implemented in the power system simulation tool PSS®NETOMAC. Based on the measurement data for different types of EVs three standardized harmonic EV models were developed and parametrized. Further, the identified harmonic models are used by the computation of load flow in a modeled, German power distribution system. As a benchmark, a case scenario was studied regarding a high market penetration of EVs in the year 2030 for Germany. The impact of the EV charging on the power distribution system was analyzed and evaluated with valid power quality standards.

X-ray ptychography, a powerful scanning lensless imaging technique, has become attractive for nondestructively imaging internal structures at nanoscale. Stage positioning overhead in conventional step-scan ptychography is one of the limiting factors on the imaging throughput. In this work, we demonstrate the use of advanced fly scan ptychography to achieve high-resolution ptychograms of modern integrated circuits on a large field-of-view at millimeter scale. By completely removing stage overheads between scan points, the imaging time for millimeter-size sample can be significantly reduced. Furthermore, we implement the orthogonal probe relaxation technique to overcome the variation of illumination across the large scan area as well as local vibrations. The capability of x-ray ptychography shown here is broadly applicable for various studies, which requires both high spatial resolution and large scan area.

Among different techniques based on x-ray nanoimaging, ptychography has become a popular tool to study specimens at nanometer-scale resolution without the need of using high-resolution optics that requires very stringent manufacturing processes. This high-resolution imaging method is compatible with other imaging modalities acquired in scanning microscopy. At the Advance Photon Source (APS), we have developed two fluorescence microscopes for simultaneous ptychography and fluorescence imaging which together provide a powerful technique to study samples in biology, environmental science, and materials science. Combined with different tilted sample projections, such correlative methods can yield high-resolution 3D structural and chemical images. More recent work has been focused on the development of a fast ptychography instrument called the Velociprobe which is built to take advantage of the over 100 times higher coherent flux provided by the coming APS upgrade source. The Velociprobe uses high-bandwidth accurate interferometry and advanced motion controls with fast continuous scanning schemes which are optimized for large-scale samples and 3D high-resolution imaging. This instrument has been demonstrated to obtain sub-10 nm resolution with different high-photon-efficient scanning schemes using fast data acquisition rate up to 3 kHz (currently limited by detector's full continuous frame rate). A ptychographic imaging rate of 100 _m2/second with a sub-20 nm spatial resolution was shown in this paper.

As a scanning version of coherent diffraction imaging (CDI), X-ray ptychography has become a popular and very successful method for high-resolution quantitative imaging of extended specimens. The requirements of mostly coherent illumination and the scanning mechanism limit the throughput of ptychographic imaging. In this paper, we will introduce the methods we use at the Advanced Photon Source (APS) to achieve highthroughput ptychography by optimizing the parameters of the illumination beam. One work we have done is increasing the illumination flux by using a double-multilayer monochromator (DMM) optics with about 0.8% bandwidth. Compared with our double-crystal monochromator (DCM) optics with 0.01% bandwidth, this DMM optics provides around 20 times more flux. A multi-wavelength reconstruction method has been implemented to deal with the consequential degraded temporal coherence from such an illumination to ensure high-quality reconstruction. In the other work, we adopt a novel use of at-top focusing optics to generate a at-top beam with the diameter of about 1.5 μm on the focal plane. The better uniformity of the probe and the large beam size allow one to significantly increase the step size in ptychography scans and thereby the imaging efficiency.

Motivated by the Advanced Photon Source Upgrade (APS-U), a new hard X-ray microscope called “Velociprobe” has been recently designed and built for fast ptychographic imaging with high spatial resolution. We are addressing the challenges of high-resolution and fast scanning with novel hardware/stage designs, new positioner control designs, and new data acquisition strategies, including the use of high bandwidth interferometric measurements. The use of granite, air-bearing-supported stages provides the necessary long travel ranges for coarse motion to accommodate real samples and variable energy operation while remaining highly stable during fine scanning. Scanning the low-mass zone plate enables high-speed high-precision motion of the probe over the sample. Our primary goal is to use this instrument to demonstrate sub-10 nm spatial resolution ptychography over a 1-square-micron area in under 10 seconds. We have also designed the instrument to take advantage of the upgraded source when the APS-U is completed. This presentation will describe the unique designs and characteristics of this instrument, and some preliminary data obtained during the instrument commission.

Motivated by the advanced photon source upgrade, a new hard X-ray microscope called "Velociprobe" has been recently designed and built for fast ptychographic imaging with high spatial resolution. We are addressing the challenges of high-resolution and fast scanning with novel hardware designs, advanced motion controls, and new data acquisition strategies, including the use of high-bandwidth interferometric measurements. The use of granite, air-bearing-supported stages provides the necessary long travel ranges for coarse motion to accommodate real samples and variable energy operation while remaining highly stable during fine scanning. Scanning the low-mass zone plate enables high-speed and high-precision motion of the probe over the sample. With an advanced control algorithm implemented in a closed-loop feedback system, the setup achieves a position resolution (3σ) of 2 nm. The instrument performance is evaluated by 2D fly-scan ptychography with our developed data acquisition strategies. A spatial resolution of 8.8 nm has been demonstrated on a Au test sample with a detector continuous frame rate of 200 Hz. Using a higher flux X-ray source provided by double-multilayer monochromator, we achieve 10 nm resolution for an integrated circuit sample in an ultrafast scan with a detector's full continuous frame rate of 3000 Hz (0.33 ms per exposure), resulting in an outstanding imaging rate of 9 × 104 resolution elements per second.

Zone plates are diffractive focusing optics capable of nanometer focusing but limited focusing efficiency at hard x-ray energy. A smaller focus spot is possible by reducing the outer zone width (OZW) while increasing the zone height will generally increase focusing efficiency. The combination of thick zones with small outer zone width, or high aspect ratio, for better performing zone plates is not feasible with state-of-the-art fabrication methods and requires other methods to achieve the aspect ratio desired. Near-field stacking involves two zone plates with the same dimensions and aligning them within the depth of focus in the beam direction and one third of the OZW in the transverse direction. Due to the depth of focus limitation, stacking more than 2 zone plates is extremely difficult, so a new method was proposed and developed to stack zone plates in the intermediate field. Multiple stacking apparatuses were assembled and tested. We will report on results from stacking 80-nm OZW zone plates from a near-field stacking experiment at 10 keV X-ray energy and intermediate field stacking 6 zone plates at 27 keV X-ray energy. We will also present findings on how to combine the stacking techniques.

Hard X-ray fluorescence microscopy is one of the most sensitive techniques to perform trace elemental analysis of unsectioned biological samples, such as cells and tissues. As the spatial resolution increases beyond sub-micron scale, conventional sample preparation method, which involves dehydration, may not be sufficient for preserving subcellular structures in the context of radiation-induced artifacts. Imaging of frozen-hydrated samples under cryogenic conditions is the only reliable way to fully preserve the three dimensional structures of the samples while minimizing the loss of diffusible ions. To allow imaging under this hydrated “natural-state” condition, we have developed the Bionanoprobe (BNP), a hard X-ray fluorescence nanoprobe with cryogenic capabilities, dedicated to studying trace elements in frozen-hydrated biological systems. The BNP is installed at an undulator beamline at Life Sciences Collaboration Access Team at the Advanced Photon Source. It provides a spatial resolution of 30 nm for fluorescence imaging by using Fresnel zone plates as nanofocusing optics. Differential phase contrast imaging is carried out in parallel to fluorescence imaging by using a quadrant photodiode mounted downstream of the sample. By employing a liquid-nitrogen-cooled sample stage and cryo specimen transfer mechanism, the samples are well maintained below 110 K during both transfer and X-ray imaging. The BNP is capable for automated tomographic dataset collection, which enables visualization of internal structures and composition of samples in a nondestructive manner. In this presentation, we will describe the instrument design principles, quantify instrument performance, and report the early results that were obtained from frozen-hydrated whole cells.

The Bionanoprobe has been developed to study trace elements in frozen-hydrated biological systems with sub-100 nm spatial resolution. Here its performance is demonstrated and first results reported., Hard X-ray fluorescence microscopy is one of the most sensitive techniques for performing trace elemental analysis of biological samples such as whole cells and tissues. Conventional sample preparation methods usually involve dehydration, which removes cellular water and may consequently cause structural collapse, or invasive processes such as embedding. Radiation-induced artifacts may also become an issue, particularly as the spatial resolution increases beyond the sub-micrometer scale. To allow imaging under hydrated conditions, close to the ‘natural state’, as well as to reduce structural radiation damage, the Bionanoprobe (BNP) has been developed, a hard X-ray fluorescence nanoprobe with cryogenic sample environment and cryo transfer capabilities, dedicated to studying trace elements in frozen-hydrated biological systems. The BNP is installed at an undulator beamline at sector 21 of the Advanced Photon Source. It provides a spatial resolution of 30 nm for two-dimensional fluorescence imaging. In this first demonstration the instrument design and motion control principles are described, the instrument performance is quantified, and the first results obtained with the BNP on frozen-hydrated whole cells are reported.

We report on design and performance of a high-resolution x-ray monochromator with a spectral bandwidth of ΔE(X) ≃ 1.5 meV, which operates at x-ray energies in the vicinity of the backscattering (Bragg) energy E(H) = 13.903 keV of the (008) reflection in diamond. The monochromator is utilized for high-energy-resolution diffraction characterization of diamond crystals as elements of advanced x-ray crystal optics for synchrotrons and x-ray free-electron lasers. The monochromator and the related controls are made portable such that they can be installed and operated at any appropriate synchrotron beamline equipped with a pre-monochromator.

A dedicated in-vacuum coherent x-ray diffraction microscope was installed at the 2-ID-B beamline of the Advanced Photon Source for use with 0.7-2.9 keV x-rays. The instrument can accommodate three common implementations of diffractive imaging; plane wave illumination; defocused-probe (Fresnel diffractive imaging) and scanning (ptychography) using either a pinhole, focused or defocused probe. The microscope design includes active feedback to limit motion of the optics with respect to the sample. Upper bounds on the relative optics-to-sample displacement have been measured to be 5.8 nm(v) and 4.4 nm(h) rms/h using capacitance micrometry and 27 nm/h using x-ray point projection imaging. The stability of the measurement platform and in-vacuum operation allows for long exposure times, high signal-to-noise and large dynamic range two-dimensional intensity measurements to be acquired. Finally, we illustrate the microscope's stability with a recent experimental result.