Journal ArticlePtychographic X-ray speckle tracking with multi-layer Laue lens systemsMorgan, Andrew J; Murray, Kevin T; Prasciolu, Mauro; Fleckenstein, Holger; Yefanov, Oleksandr; Villanueva-Perez, Pablo; Mariani, Valerio; Domaracky, Martin; Kuhn, Manuela; Aplin, Steve; Mohacsi, Istvan; Messerschmidt, Marc; Stachnik, Karolina; Du, Yang; Burkhart, Anja; Meents, Alke; Nazaretski, Evgeny; Yan, Hanfei; Huang, Xiaojing; Chu, Yong S; Chapman, Henry N; Bajt, Saša<p>The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilize their capability for imaging and probing biological cells, nano-devices and functional matter on the nanometre scale with chemical sensitivity. Hard X-rays are ideal for high-resolution imaging and spectroscopic applications owing to their short wavelength, high penetrating power and chemical sensitivity. The penetrating power that makes X-rays useful for imaging also makes focusing them technologically challenging. Recent developments in layer deposition techniques have enabled the fabrication of a series of highly focusing X-ray lenses, known as wedged multi-layer Laue lenses. Improvements to the lens design and fabrication technique demand an accurate, robust,<italic>in situ</italic>and at-wavelength characterization method. To this end, a modified form of the speckle tracking wavefront metrology method has been developed. The ptychographic X-ray speckle tracking method is capable of operating with highly divergent wavefields. A useful by-product of this method is that it also provides high-resolution and aberration-free projection images of extended specimens. Three separate experiments using this method are reported, where the ray path angles have been resolved to within 4 nrad with an imaging resolution of 45 nm (full period). This method does not require a high degree of coherence, making it suitable for laboratory-based X-ray sources. Likewise, it is robust to errors in the registered sample positions, making it suitable for X-ray free-electron laser facilities, where beam-pointing fluctuations can be problematic for wavefront metrology.</p>Journal of Applied Crystallography2020-08-0110587755Journal of Applied Crystallography534927 to 9361600-5767https://doi.org/10.1107/s16005767200069251231306National Science Foundation