Optimization of off-axis electron holography performed with femtosecond electron pulses

Florent Houdellier (1) , Giuseppe Mario Caruso (2) , Sébastien J. Weber (2) , M.J. Hÿtch (1) , Christophe Gatel (1) , Arnaud Arbouet

1 CEMES-I3EM - Interférométrie, In situ et Instrumentation pour la Microscopie Electronique
2 CEMES - Centre d'élaboration de matériaux et d'études structurales

We report on electron holography experiments performed with femtosecond electron pulses in an ultrafast coherent Transmission Electron Microscope based on a laser-driven cold field emission gun. We first discuss the experimental requirements related to the long acquisition times imposed by the low emission/probe current available in these instruments. The experimental parameters are first optimized and electron holograms are then acquired in vacuum and on a nano-object showing that useful physical properties can nevertheless be extracted from the hologram phase in pulsed condition. Finally, we show that the acquisition of short exposure time holograms assembled in a stack, combined with a computer-assisted shift compensation of usual instabilities encountered in holography, such as beam and biprism wire instabilities, can yield electron holograms acquired with a much better contrast paving the way to ultrafast time-resolved electron holography.

Mots clés: Ultrafast Transmission Electron Microscopy; electron holography; cold field emission; femtosecond laser

Domaines: Matériaux; Optique / photonique; Traitement du signal et de l'image [eess.SP]; Electromagnétisme; Physique des accélérateurs [physics.acc-ph]; Physique Quantique [quant-ph]; Physique des Hautes Energies - Expérience [hep-ex]; Optique [physics.optics]

Florent Houdellier, Giuseppe Mario Caruso, Sébastien J. Weber, M.J. Hÿtch, Christophe Gatel, et al.. Optimization of off-axis electron holography performed with femtosecond electron pulses. Ultramicroscopy, 2019, ⟨10.1016/j.ultramic.2019.03.016⟩. ⟨hal-02080673⟩