Evaluation a 48 pixel programmable phase plate for electron wavefront shaping

Abstract text (incl. figure legends and references)

We report on advances in the development of a versatile programmable phase plate for use in electron microscopy. The current design provides up to 48 individually addressable electrostatic phase shifting elements that can be laid out in multiple design patterns depending on the target application. The phase plate state can be synchronously updated at up to 100 kHz rate providing an attractive route for high speed adaptive algorithms shaping the electron probe while optimizing a goal function. We discuss different phase plate implementations and their usefulness towards applications. We show the realization of dipolar, quadrupolar and vortex phase symmetries in sub nm electron probes when placing the phase plate in the condenser plane of a modern STEM microscope. We demonstrate adaptive algorithms maximizing for contrast in HAADF STEM images as well as discussing their prospects for focusing inside thick samples, increasing depth of field and use in ptychography.

Figure 1. Example of two prototype phase plate realisations showing a 36 pixels cartesian design (left) and a polar segmented 48 pixel design.

[1] J. Verbeeck et al. "Demonstration of a 2×2 programmable phase plate for electrons." Ultramicroscopy 190 (2018): 58-65.

[2] Patents EP3474308, US11062872 B2.

[3] The authors acknowledge the financial support of the Research Foundation Flanders (FWO, Belgium) project G042820N. The ADAPTEM project is funded by the European Research Council as an ERC POC project under grant nr: DLV-789598.