Coherence Seminar: X-ray sparse-angle Bragg ptychography

Start Date
09-11-2018 11:00
Room 1-10, Common Building
Speaker's name
Dr. Peng Li
Speaker's institute
Institut Fresnel (CNRS) - Marseille
Contact name
Sabine Schreiber
Host name
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X-ray Bragg ptychography is a scanning coherent diffraction imaging microscopy technique that can produce 3D maps of the crystalline structure of an extended nanostructured crystal at about 10nm resolution. With sparse-angle Bragg ptychography, the 3D maps can be extracted from an extremely undersampled data-set. This new strategy substantially reduces the acquisition time and mitigates problems, linked to radiation damage and instabilities, faced by conventional Bragg ptychography. However, the success of the image reconstruction is based on a good knowledge of the probe, whose uncertainties degrade the object reconstruction. 

In this talk, we solve this problem by proposing a simultaneous reconstruction of the probe and object functions. This is based on a strong but natural constraint of the probe properties. We demonstrate our approach on a He-implanted poly-crystalline Tungsten sample measured at ID01-ESRF. These findings open new possibilities for this imaging technique.

The work is funded by European Research Council (H2020 grant #72881). Collaborations from Felix Hofmann (University of Oxford) and Steven Leake (ID01, ESRF) are acknowledged.
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