Alternating Projection, Ptychographic Imaging and Phase Synchronization
  We demonstrate necessary and sufficient conditions of the local convergence of the alternating projection algorithm to a unique solution up to a global phase factor. Additionally, for the ptychography imaging problem, we discuss phase synchronization and graph connection Laplacian, and show how to construct an accurate initial guess to accelerate convergence speed to handle the big imaging data in the coming new light source era. 
Stefano Marchesini, Yu-Chao Tu, Hau-tieng Wu
math.OC physics.optics stat.ME