Relaxing Direct Ptychography Sampling Requirements via Parallax Imaging Insights

TL;DR

This paper introduces a novel approach that leverages parallax imaging insights to relax sampling constraints in direct ptychography, enabling higher resolution imaging with less stringent sampling requirements.

Contribution

It formulates parallax imaging as a quadratic approximation within ptychography, allowing for effective upsampling and improved resolution without increased sampling density.

Findings

Validated through simulated reconstructions

Demonstrated improved resolution with relaxed sampling

Applicable to experimental data

Abstract

Direct ptychography enables the retrieval of information encoded in the phase of an electron wave passing through a thin sample by deconvolving the interference effects of a converged probe with known aberrations. Under the weak phase object approximation, this permits the optimal transfer of information using non-iterative techniques. However, the achievable resolution of the technique is traditionally limited by the probe step size -- setting stringent Nyquist sampling requirements. At the same time, parallax imaging has emerged as a dose-efficient phase-retrieval technique which relaxes sampling requirements and enables scan-upsampling. Here, we formulate parallax imaging as a quadratic approximation to part of the direct ptychography kernel and use this insight to enable upsampling in direct ptychography. We validate our analytical results numerically using simulated and experimental reconstructions.