Optical vectorial ptychography

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Principal investigator : Patrick Ferrand

In the optical regime, ptychography is becoming a new competitive microscopy method mostly thanks to its capability to image quantitatively the phase shift introduced by the sample.

We have established a vectorial formalism that allows to use ptychography even on anisotropic (e.g., birefringent, but not only) specimens. We have demonstrated the capability of of vectorial ptychography to map the four parameters of the Jones matrix of an anisotropic specimens, and therefore to quantify a wide range of optical material properties, including power transmittance, optical path difference, diattenuation, retardance, fast-axis orientation, and even more. Recently we also established how to extract structural parameters from this information.

**3D orientation of the crystallographic c-axis inside oyster shell calcite prisms. [From Baroni et al., Phys Rev App 2020].**

3D orientation of the crystallographic c-axis inside oyster shell calcite prisms. [From Baroni et al., Phys Rev App 2020].

Our method is reference-free, since the jones-matrix map is estimated jointly with the illumination probes. This opens for vectorial ptychography new possibilities towards imaging specimen having anisotropic properties, including biominerals, metasurfaces, etc. Imaging complicated vectorial beams has also been demonstrated, as illustrated below :

Fundings : This work is funded by the French ANR under contract no ANR-11-BS10-0005 and by the European Research Council (ERC) under the European Union’s Horizon H2020 research and innovation program grant agreement No 724881.

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