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In recent years, X‐ray speckle‐tracking techniques have emerged as viable tools for wavefront metrology and sample imaging applications. These methods are based on the measurement of near‐field images. Thanks to their simple experimental setup, high angular sensitivity and compatibility with low‐coherence sources, these methods have been actively developed for use with synchrotron and laboratory light sources. Not only do speckle‐tracking techniques give the potential for high‐resolution imaging, but they also provide rapid and robust characterization of aberrations of X‐ray optical elements, focal spot profiles, and sample position and transmission properties. In order to realize these capabilities, software implementations are required that are equally rapid and robust. To address this need, a software suite has been developed for the ptychographic X‐ray speckle‐tracking technique, an X‐ray speckle‐based method suitable for highly divergent wavefields. The software suite is written in Python 3, with an OpenCL back end for GPU and multi‐CPU core processing. It is accessible as a Python module, through the command line or through a graphical user interface, and is available as source code under Version 3 or later of the GNU General Public License. [ABSTRACT FROM AUTHOR]

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, in situ 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. [ABSTRACT FROM AUTHOR]

High‐resolution Bragg diffraction from aerosolized single granulovirus nanocrystals using an X‐ray free‐electron laser is demonstrated. The outer dimensions of the in‐vacuum aerosol injector components are identical to conventional liquid‐microjet nozzles used in serial diffraction experiments, which allows the injector to be utilized with standard mountings. As compared with liquid‐jet injection, the X‐ray scattering background is reduced by several orders of magnitude by the use of helium carrier gas rather than liquid. Such reduction is required for diffraction measurements of small macromolecular nanocrystals and single particles. High particle speeds are achieved, making the approach suitable for use at upcoming high‐repetition‐rate facilities. [ABSTRACT FROM AUTHOR]

The intensities of far-field diffraction patterns of orientationally aligned molecules obey Wilson statistics, whether those molecules are in isolation (giving rise to a continuous diffraction pattern) or arranged in a crystal (giving rise to Bragg peaks). Ensembles of molecules in several orientations, but uncorrelated in position, give rise to the incoherent sum of the diffraction from those objects, modifying the statistics in a similar way as crystal twinning modifies the distribution of Bragg intensities. This situation arises in the continuous diffraction of laser-aligned molecules or translationally disordered molecular crystals. This paper develops the analysis of the intensity statistics of such continuous diffraction to obtain parameters such as scaling, beam coherence and the number of contributing independent object orientations. When measured, continuous molecular diffraction is generally weak and accompanied by a background that far exceeds the strength of the signal. Instead of just relying upon the smallest measured intensities or their mean value to guide the subtraction of the background, it is shown how all measured values can be utilized to estimate the background, noise and signal, by employing a modified `noisy Wilson' distribution that explicitly includes the background. Parameters relating to the background and signal quantities can be estimated from the moments of the measured intensities. The analysis method is demonstrated on previously published continuous diffraction data measured from crystals of photosystem II [Ayyer et al. (2016), Nature, 530, 202-206]. [ABSTRACT FROM AUTHOR]

This article describes a free and open-source data analysis utility designed for fast online feedback during serial X-ray diffraction and scattering experiments: OnDA (online data analysis). Three complete real-time monitors for common types of serial X-ray imaging experiments are presented. These monitors are capable of providing the essential information required for quick decision making in the face of extreme rates of data collection. In addition, a set of modules, functions and algorithms that allow developers to modify the provided monitors or develop new ones are provided. The emphasis here is on simple, modular and scalable code that is based on open-source libraries and protocols. OnDA monitors have already proven to be invaluable tools in several experiments, especially for scoring and monitoring of diffraction data during serial crystallography experiments at both free-electron laser and synchrotron facilities. It is felt that in the future the kind of fast feedback that OnDA monitors provide will help researchers to deal with the expected very high throughput data flow at next-generation facilities such as the European X-ray free-electron laser. [ABSTRACT FROM AUTHOR]