52 doi:10.1017/S1431927618012692 Microsc. Microanal. 24 (Suppl 2), 2018 © Microscopy Society of America 2018 Performance and Ongoing Development of the Velociprobe, a Fast Hard X-ray Nanoprobe for High-Resolution Ptychographic Imaging Jeffrey A. Klug 1,* , Junjing Deng 1 , Curt Preissner 1 , Christian Roehrig 1 , Sheikh T. Mashrafi 2 , Maoyu Wang 3 , Zhenxing Feng 3 , Michael Wojcik 1 , Max Wyman 1 , Keenan Lang 1 , Zhonghou Cai 1 , Barry Lai 1 , and Stefan Vogt 1 1. Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA 2. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 3. School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA * Corresponding author, jklug@anl.gov The Velociprobe is a next generation X-ray microscope built to make efficient use of the dramatic increase in coherent flux from the Advanced Photon Source Upgrade (APS-U) [1,2]. Fast ptychographic imaging with high spatial resolution is achieved using novel hardware/stage designs, new positioner control designs, and new data acquisition strategies, including the use of high bandwidth interferometric measurements. The capabilities and performance of the current instrument are demonstrated with ptychographic measurements of micron-scale complex oxide particles. A planned upgrade to extend the fast-scanning range and improve the 3D imaging capability of the Velociprobe is discussed. The Velociprobe instrument at APS beamline 2-ID-D was designed and built to optimize stability during high-speed optics scanning for ptychography and scanning probe measurements with an emphasis on 2D imaging. The use of novel granite, air-bearing-supported stages provides high stability during imaging. Fast, on-the-fly scanning is implemented by scanning the low-mass zone plate across a small area at high speed. Unlike current commonly used fly-scan schemes in which only one axis is fly-scanned, both axes on the Velociprobe are continuously moved throughout the scan. This is achieved by an optimized control algorithm providing large tracking bandwidth and good positioning resolution using National Instruments FPGA-based control hardware [3]. With the current instrument, a ptychographic fly-scan of a 4 µm  4 µm area with diffraction patterns captured every 50 nm in both X and Y axes (~6400 exposures in total) can be completed in as little as 2 seconds at a speed of 0.16 mm/s. The speed is limited by the frame rate of the detector (3 kHz) rather than the optics scanning mechanics (5.7 mm/s). The spatial resolution at 3 kHz is flux limited, with ~30 nm or ~17 nm achieved with a double-crystal (~5  10 8 ph/s) or double-multilayer monochromator (~8  10 9 ph/s), respectively. Figure 1(a) shows the schematic of a typical ptychography scan on the Velociprobe. To benchmark the performance of the Velociprobe, 2D ptychography measurements of micron-scale perovskite particles were performed and analysed. In the ptychography experiment, 10 keV X-rays from an APS undulator A were spectrally filtered using a double-crystal Si (111) monochromator. A Fresnel zone plate with an outermost zone width of 50 nm was used to focus the coherent X-ray beam down to a spot size of approximately 60 nm. LaFe 0.3 Co 0.7 O 3 perovskite particles were placed on a Si 3 N 4 window which was put 100 µm downstream of the focus. The zone plate was continuously moved in a snake-pattern trajectory (see Fig. 1(a)) at a speed of ~2.5 µm/s. Far field diffraction patterns were collected with an area detector (Dectris Eiger X 500K) with 75 µm pixel size. The detector was positioned 2 m downstream of the sample and triggered by the FPGA every 20 ms (time-based triggering). The three- https://doi.org/10.1017/S1431927618012692 Downloaded from https://www.cambridge.org/core. IP address: 172.245.220.243, on 16 Aug 2019 at 12:05:50, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms.