Efficient illumination angle self-calibration in Fourier ptychography

TL;DR

This paper introduces a fast and robust self-calibration algorithm for Fourier ptychography that accurately estimates illumination angles using only experimental data, improving image quality and correcting misalignments.

Contribution

The proposed method combines direct angle estimation with spectral correlation refinement, enabling efficient calibration across various illumination setups.

Findings

Effective correction of large and small misalignments.

Applicable to multiple illumination sources including LED arrays and lasers.

Enhances image quality in 2D and 3D Fourier ptychography.

Abstract

Fourier ptychography captures intensity images with varying source patterns (illumination angles) in order to computationally reconstruct large space-bandwidth-product images. Accurate knowledge of the illumination angles is necessary for good image quality; hence, calibration methods are crucial, despite often being impractical or slow. Here, we propose a fast, robust, and accurate self-calibration algorithm that uses only experimentally-collected data and general knowledge of the illumination setup. First, our algorithm makes a direct estimate of the brightfield illumination angles based on image processing. Then, a more computationally-intensive spectral correlation method is used inside the iterative solver to further refine the angle estimates of both brightfield and darkfield images. We demonstrate our method for correcting large and small misalignment artifacts in both 2D and 3D Fourier ptychography with different source types: an LED array, a galvo-steered laser, and a high-NA quasi-dome LED illuminator.