Abstract

Bragg coherent diffraction imaging (BCDI) is a powerful technique to explore the local strain state and morphology of microscale crystals. The method can potentially reach nanometer-scale spatial resolution thanks to the advances in synchrotron design that dramatically increase coherent flux. However, there are experimental bottlenecks that may limit the image reconstruction quality from future high signal-to-noise ratio measurements. In this work we show that angular uncertainty of the sample orientation with respect to a fixed incoming beam is one example of such a factor, and we present a method to mitigate the resulting artifacts. On the basis of an alternative formulation of the forward problem, we design a phase retrieval algorithm which enables the simultaneous reconstruction of the object and determination of the exact angular position corresponding to each diffraction pattern in the data set. We have tested the algorithm performance on simulated data for different degrees of angular uncertainty and signal-to-noise ratio.

Highlights

  • Bragg coherent diffraction imaging (BCDI) is a lens-less technique which explores the local morphology and structural imperfections of micro-crystalline samples, shedding light on topics which are central to material science, for example materials synthesis or device performance[1,2,3,4,5,6,7]

  • Such angular uncertainty can come about when a stationary incident beam illuminates a sample undergoing uncontrolled rotation or imprecise experimental stages, difficult-to-stabilize sample environments or, even, to the torque exerted by the x-ray beam on the sample

  • Current BCDI inversion algorithms are based on the formulation of the forward problem which uses the 3D Fourier transformation to retrieve an image of the crystal ρ from the 3D diffracted wave-front Ψ in the far-field: Ψ = 3D[ρ]1,2,14

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Summary

Introduction

Bragg coherent diffraction imaging (BCDI) is a lens-less technique which explores the local morphology and structural imperfections of micro-crystalline samples, shedding light on topics which are central to material science, for example materials synthesis or device performance[1,2,3,4,5,6,7]. This approach allows the joint estimation of the object and the set of incident sample angles queried in the measurement.

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Conclusion

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