electron ptychography

**Electron Ptychography** is the **application of ptychographic reconstruction to STEM data** — using 4D-STEM datasets (a convergent beam electron diffraction pattern at each scan position) to computationally reconstruct the specimen with resolution approaching the electron wavelength (~2 pm). **How Does Electron Ptychography Work?** - **4D-STEM**: At each scan position, record the full 2D diffraction pattern (not just integrated intensity). - **Overlap**: Ensure adjacent probe positions have significant overlap (typically 50-80%). - **Reconstruct**: Iterative algorithms recover the complex specimen transmission function. - **Resolution**: Has achieved ~0.39 Å resolution — the highest resolution imaging ever demonstrated. **Why It Matters** - **Record Resolution**: Electron ptychography holds the record for the highest resolution imaging of any technique. - **Light Elements**: Phase contrast is sensitive to light elements (H, Li, O) that HAADF cannot see. - **Dose Efficient**: Can achieve high resolution at lower electron doses, important for beam-sensitive materials. **Electron Ptychography** is **the ultimate resolution technique** — computationally reconstructing images at resolutions approaching the electron wavelength itself.