Optimized Phase-Retrieval Technique for Coherent Diffractive Microscopy: Guided Ptychography Iterative Engine

We have developed a guided ptychography iterative engine (gPIE) algorithm that applies the concept of optimization to the conventional ePIE (extended ptychography iterative engine) approach. Instead of accessing a random or spiral trajectory among the collected diffraction patterns to implement the phase-retrieval, gPIE guides the searching direction through the local minimum and minimizes the cost function, which is the difference between the calculated intensities and the experimental ones, to approach the global minimum. Compared with ePIE, gPIE robustly reconstructs a more accurate sample and illumination, thus revealing the correct surface topology. The feasibility of gPIE was verified experimentally by acquiring sequential diffraction patterns from a UV laser.