A novel device that can be used as a tunable support-free phase plate for transmission electron microscopy of weakly scattering specimens is described. The device relies on the generation of a controlled phase shift by the magnetic field of a segment of current-carrying wire that is oriented parallel or antiparallel to the electron beam. The validity of the concept is established using both experimental electron holographic measurements and a theoretical model based on Ampere's law. Computer simulations are used to illustrate the resulting contrast enhancement for studies of biological cells and macromolecules.
@article{arxiv.1702.02029,
title = {Tunable Ampere phase plate for low dose imaging of biomolecular complexes},
author = {Amir H. Tavabi and Marco Beleggia and Vadim Migunov and Alexey Savenko and Sara Sandin and Ozan Öktem and Rafal E. Dunin-Borkowski and Giulio Pozzi},
journal= {arXiv preprint arXiv:1702.02029},
year = {2017}
}