Practical implementation of high-resolution electron ptychography and comparison with off-axis electron holography

Area of Science:

• Coherent diffractive imaging
• Transmission electron microscopy
• Materials science

Background:

• Ptychography is an advanced imaging technique using overlapping probes to reconstruct an object's electron wave transmission.
• Recent advances in detectors and algorithms have made ptychography practical for transmission electron microscopy.
• It offers quantitative phase information at high spatial resolution, comparable to electron holography.

Purpose of the Study:

• To detail the workflow for practical ptychography implementation in transmission electron microscopy.
• To compare and contrast high-resolution ptychography with electron holography using experimental data and modeling.
• To explore the similarities and differences in phase information retrieval between the two techniques.

Main Methods:

• Utilizing a well-calibrated scanning transmission electron microscope.
• Implementing a managed workflow for calibration, data acquisition, and reconstruction.
• Employing acquisition management software to streamline the ptychography process.
• Comparing ptychography results with electron holography through experimental data and modeling.

Main Results:

• Ptychography provides a detailed electron transmission model, including phase and amplitude changes.
• The technique does not require an electron bi-prism or a minimally structured adjacent region, unlike off-axis electron holography.
• Both ptychography and electron holography show phase dependence on crystalline orientation due to dynamical scattering.
• The specific nature of phase variation differs between techniques, but both yield equally useful information.

Conclusions:

• Ptychography is a viable alternative or complement to electron holography for high-resolution phase imaging in transmission electron microscopy.
• A well-managed workflow and specialized software are crucial for successful ptychography implementation.
• Despite differences in phase variation, both ptychography and electron holography provide valuable insights into material properties.