Accelerated convergence extended ptychographical iterative engine using multiple axial intensity constraints.

The extended ptychographical iterative engine (ePIE) is widely applied in the field of ptychographic imaging due to its great flexibility and computational efficiency. A technique of ePIE with multiple axial intensity constraints, which is called MAIC-PIE, is proposed to drastically improve the convergence speed and reduce the calculation time. This technique requires that the diffracted light from the sample is propagated to the multiple individual axial planes, which can be achieved by using the beam splitter and multiple CCDs. In this technique, an additional intensity constraint is involved in the iterative process that makes for building the reasonable guesses of the probe and object in the first few iterations and accelerating the convergence. Simulations and experiments have verified that MAIC-PIE behaves good performance with fast convergence. The great performance and limited computational complexity make it a very attractive and promising technique for ptychographic imaging.