ptychography

**Ptychography** is a **computational imaging technique that recovers both the amplitude and phase of a transmitted wave by scanning a coherent probe across overlapping positions** — using iterative algorithms to reconstruct the complex specimen transmission function with resolution beyond the diffraction limit. **How Does Ptychography Work?** - **Scan**: Move a coherent probe (light or electrons) across the sample with overlapping illumination areas. - **Diffraction Patterns**: Record a diffraction pattern at each position. - **Reconstruction**: Iterative phase retrieval algorithms (ePIE, rPIE) recover both probe and specimen functions. - **Resolution**: Not limited by lens quality — limited only by the maximum scattering angle detected. **Why It Matters** - **Lens-Free Imaging**: Resolution is determined by the detector, not the lens system -> surpasses lens resolution limits. - **Phase Information**: Recovers the phase of the transmitted wave, which carries information about electric/magnetic fields and composition. - **Versatile**: Works with X-rays (synchrotron), electrons (TEM), and visible light. **Ptychography** is **lensless super-resolution imaging** — using computational methods to reconstruct images with resolution beyond what any lens can achieve.