The Velociprobe: A next-generation, ultra-high-resolution X-ray ptychographic microscope

The U.S. Department of Energy’s Advanced Photon Source (APS) at Argonne National Laboratory produces ultra-bright, high-energy X-rays for research on the structure and function of materials. The APS will undergo a major upgrade in the upcoming years in order to provide over 100 times more coherent photons.

A new article describes an ultra-stable, ultra-fast X-ray ptychographic microscope designed to demonstrate the technologies and techniques necessary to take full advantage of the APS Upgrade. The Velociprobe employs fly-scan ptychography, which involves a continuous motion scan instead of a step scan. The instrumentation must move quickly while remaining stable and accurate in terms of positioning.

The researchers looked at the design of X-ray microscopes in a new way by asking themselves how a device could be made both ultra-stable and ultra-fast. They integrated a number of novel concepts into the Velociprobe to achieve this goal, such as an ultra-stable coarse-motion system made of granite-based air bearing stages.

The fast fly-scanning is enabled by the integration of interferometers to measure relative optics-to-sample position down to the level of a few nanometers. Such precision enables precise feedback control and accurate positioning information for data reconstruction. The Velociprobe is one of the fastest X-ray ptychographic instruments currently in existence.

The study demonstrates the possibility of scanning and collecting data fast enough to make use of all the photons available after the APS Upgrade. The researchers hope that this will open up new avenues for experiments across scales, such as investigations of spatially or temporally rare events, dynamic studies beyond current optical resolution limits and investigations of fine structural detail in the large-scale context of functional materials like solar cells.

Source: “The Velociprobe: An ultrafast hard X-ray nanoprobe for high-resolution ptychographic imaging,” by Junjing Deng, Curt Preissner, Jeffrey A. Klug, Sheikh Mashrafi, Christian Roehrig, Yi Jiang, Yudong Yao, Michael J. Wojcik, Max D. Wyman, David Vine, Ke Yue, Si Chen, Tim Mooney, Maoyu Wang, Zhenxing Feng, Dafei Jin, Zhonghou Cai, Barry Lai, and Stefan Vogt, Review of Scientific Instruments (2019). The article can be accessed at http://doi.org/10.1063/1.5103173 .