LoRePIE: ℓ₀ regularized extended ptychographical iterative engine for low-dose and fast electron ptychography

Area of Science:

• Materials Science
• Physics
• Electron Microscopy

Background:

• Extended Ptychographical Iterative Engine (ePIE) is standard for 4-D STEM phase retrieval.
• ePIE requires substantial overlap between adjacent illuminated areas for data redundancy.

Purpose of the Study:

• To develop a regularized ePIE variant robust to low overlap ratios in 4-D STEM data.
• To assess the performance of the new algorithm on experimental and synthetic datasets.

Main Methods:

• Proposed a regularized variant of the ePIE algorithm.
• Tested the algorithm on experimental 4-D STEM data of Rotavirus particles.
• Created synthetic 4-D STEM datasets by down-sampling probe positions to simulate low overlap.

Main Results:

• The regularized ePIE achieved high-quality reconstruction of Rotavirus particles.
• Successful reconstruction was demonstrated with overlap ratios as low as 56%.

Conclusions:

• The proposed regularized ePIE algorithm enhances robustness to low overlap in 4-D STEM.
• This advancement allows for high-quality phase retrieval with reduced data acquisition requirements.