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.