Source-linked AI summary
Quantitative phase imaging via Fourier ptychographic microscopy
Xiaoze Ou, Roarke Horstmeyer, Changhuei Yang, Guoan Zheng
TL;DR
FPM addresses whether iterative reconstruction from angularly varied, low-resolution intensity images can recover quantitatively accurate phase while extending resolution beyond an objective’s cutoff. The paper compares FPM with theory and phase-shifting digital holography, then examines spatial-resolution limits and phase-enabled sample visualization.
Problem
FPM phase accuracy remained uncertain because its non-convex iterative reconstruction could produce accurate intensity images without guaranteeing quantitatively correct phase.
Method
FPM uses a fixed LED array to illuminate a sample from multiple angles, records low-resolution images through a low-NA objective, and reconstructs the high-resolution complex field computationally.
Results
FPM phase closely matches theory and digital holography for polystyrene microbeads and a human blood smear, with line-trace MSE = 0.58 µm for a red blood cell.
Takeaways & Limitations
FPM quantitative phase supports enhanced visualization and reveals sample information absent from improved-resolution intensity images.
Takeaways & Limitations
FPM phase resolution depends on the product of sample spatial resolution and thickness, while a more detailed analysis remains future work.
Abstract
from arXiv · showhide
Fourier ptychographic microscopy (FPM) is a recently developed imaging modality that uses angularly varying illumination to extend a system performance beyond the limit defined by its optical elements. The FPM technique applies a novel phase retrieval procedure to achieve both resolution enhancement and complex image recovery. In this letter, we compare FPM data to both theoretical prediction and phase-shifting digital holography measurement to show that its acquired phase maps are quantitative and artifact-free. We additionally explore the relationship between the achievable spatial and optical thickness resolution offered by a reconstructed FPM phase image. We conclude by demonstrating both enhanced visualization and the collection of otherwise unobservable sample information using FPM quantitative phase.