Aberration-independent phase-separable reconstruction parameters

Establish a choice of integration region and filter for direct-interference ptychography that makes the phase reconstruction independent of the sample amplitude regardless of probe aberrations.

Background

The paper derives an amplitude reconstruction that is separable from the sample phase for arbitrary probe aberrations, but the corresponding phase reconstruction is more difficult. The authors seek a suitable integration region and postprocessing filter that would eliminate amplitude contributions from the phase reconstruction without requiring an in-focus or aberration-corrected measurement. They report that their selected difference-of-double-overlap-regions construction performs well numerically, but do not establish analytically that any reconstruction-parameter choice has the desired aberration-independent separability.