Abstract
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.
Highlights
The X-ray speckle-tracking (XST) technique was introduced by Berujon et al (2012) and a little later by Morgan et al (2012) as a way of obtaining a quantitative measurement of the phase of a wavefield, as induced by a transmitting object, for example
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
Summary
The X-ray speckle-tracking (XST) technique was introduced by Berujon et al (2012) and a little later by Morgan et al (2012) (no relation to the current author AJM) as a way of obtaining a quantitative measurement of the phase of a wavefield, as induced by a transmitting object, for example. The analyser is typically chosen to be a thin sample with a random phase/ absorption profile that produces intensity variations (or ‘speckles’) some distance downstream, in the near field These speckles are used as fiducial markers to determine the directions of the rays in the wavefield. In the differential configuration of XST, the wavefield’s ray paths could have been determined by comparing the location of the observed speckles with those observed in an image of the same sample, but illuminated with an ideal wavefield, such that the ray path directions are known a priori Again, such an approach is impractical in cases where the optics to produce such an idealized wavefield are not available. The central goal of the speckle-tracking software suite introduced here is to solve the set of equations in equation (1) for È and Iref in terms of the recorded images In
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