phaser: A unified and extensible framework for fast electron ptychography

Abstract

We present \code{phaser}, an open-source Python package that provides a unified interface to both conventional and gradient descent-based ptychographic algorithms. Features such as mixed-state probe, probe position correction, and multislice ptychography make experimental reconstructions practical and robust. Reconstructions are specified in a declarative format and can be run from a command line, Jupyter notebook, or web interface. Multiple computational backends are supported to provide maximum flexibility. With the JAX computational backend, a six-fold improvement in iteration speed is achieved over a widely used package implemented in MATLAB, fold\_slice/PtychoShelves. We report reconstruction success for a variety of experimental datasets, and detail the effects of regularization on convergence and reconstruction quality. The software promises to speed the application and development of ptychographic methods for materials science.