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Irene Calvo Almazn1 Martin Holt1 Siddharth Maddali1 Andrew Ulvestad1 Stephan Hruszkewycz1

1, Argonne National Laboratory, Lemont, Illinois, United States

Three-dimensional coherent diffraction imaging methods including Bragg ptychography (BP) and single-particle Bragg coherent diffraction imaging (BCDI) have tremendous potential to elucidate dynamic structural properties in nanoscale crystalline volumes with especially fine sensitivity to lattice imperfections. However, especially in in-situ environments, uncertainty due to thermal drift and vibrations can affect not only the position of particle / beam, but also the incident angle. Both have detrimental effects on the final reconstructed image. In this abstract we focus on correcting angular uncertainties, and we show that the approach can be used both for BCDI and Bragg ptychography.

The novelty of our approach, inspired in the steepest descent gradient method successfully applied in transmission Bragg ptychography, lies in the calculation of a generalized gradient of the error which enables its minimization by simultaneously improving the reconstructed object and correcting for the beam position/incident angle uncertainties. This method to correct for the angular position of the diffraction pattern collected over a rocking curve scan has a wide application in the post-processing procedure of BCDI and BP measured data since the high precision control of the beam position/incident angle which is required for a high quality reconstruction is often difficult to achieve.

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