Vectorial ptychography: imaging when polarization matters, with Patrick Ferrand
Channel: LINXS
Date: 2023-05-29

The CoWork webinar series is dedicated to the exploitation of the coherence properties of X-rays for advanced materials characterization, with a special focus on inverse microscopy techniques, such as Coherent Diffraction Imaging (CDI), Ptychography and Holography. It is an introduction to Coherent X-ray imaging methods to facilitate the access to advanced microscopy techniques to new users and it welcomes all researchers intrigued by the spectacular coherence properties of X-rays produced at modern synchrotron sources – of which MAX IV is a first example. 

Bio: 
Patrick Ferrand is an associate professor at Institut Fresnel, Aix-Marseille Université, Marseille. His research mainly focuses on the development of methods of quantitative optical microscopy, to image molecular order or complex materials, based on novel data acquisition strategies (fluorescence fluctuations, control of light polarization, ptychography) and advanced computation.

Abstract: 
 Ptychography, in its most common uses, assumes that the objects to be imaged scatter light, but do not affect its state of polarization. When this assumption is not valid, we have recently shown that ptychography must be declined in a (more general) vectorial fashion, to retrieve the full set of properties of such objects. In this talk, I will remind the basic concepts related to light polarization and introduce the formalism of vectorial ptychography [1], as well as the details of its experimental [2] and numerical implementations [3]. Several recent results based on this technique will be given, from the structural imaging of biomineral materials [4,5] to the investigation of engineered metasurfaces [6,7]. This work was partially funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreements No 724881.

[1] Ferrand et al. Opt Lett 2015 https://dx.doi.org/10.1364/OL.40.005144

[2] Ferrand et al. Opt Lett 2018 https://dx.doi.org/10.1364/OL.43.000763

[3] Baroni et al. Opt Exp 2019 https://dx.doi.org/10.1364/OE.27.008143

[4] Baroni et al., Phys Rev Appl 2020 https://dx.doi.org/10.1103/PhysRevApplied.13.054028

[5] Duboisset et al., Acta Biomateriala 2022 https://dx.doi.org/10.1016/j.actbio.2022.01.024

[6] Q. Song et al., Nat Commun 2020 https://dx.doi.org/10.1038/s41467-020-16437-9

[7] Q. Song et al., Nat Commun 2021 https://dx.doi.org/10.1038/s41467-021-23908-0