Super-Resolution Structured-Illumination X-Ray Microscopy based on Fourier Decomposition

TL;DR

This paper introduces a Fourier decomposition-based super-resolution technique for transmission X-ray microscopy, enhancing resolution and enabling multimodal imaging without altering standard acquisition schemes.

Contribution

It presents a novel structured-illumination method that improves resolution by a factor of 2.2 and integrates seamlessly with existing X-ray tomography systems.

Findings

Achieved 2.2x resolution enhancement in X-ray microscopy.

Demonstrated multimodal imaging including phase-contrast and dark-field.

Enabled super-resolved transmission imaging without changing standard protocols.

Abstract

We present a structured-illumination technique for full-field super-resolution transmission X-ray microscopy, which employs Fourier spectral decomposition inspired by established methods in visible-light microscopy. A 2D grating creating this illumination is stepped across one period to acquire a set of images at unique illumination positions. The Fourier domain of each image is described as a linear combination of replicated sample information at each frequency harmonic. As this superposition is created independently of detection, it contains spatial information exceeding native detector resolution. Recovering the encoded high-frequency components enables the population of an expanded frequency space. We demonstrate the presence of additional sample information in the Fourier spectrum and introduce a method to recover it. We achieve a resolution improvement by a factor of 2.2 for the projection image of a resolution test pattern. We further demonstrate seamless integration into standard X-ray tomography acquisition schemes. The acquisition is inherently multimodal, as phase-contrast and dark-field images can be computed from the same data using methods such as unified modulated pattern analysis, while providing an additional super-resolved transmission channel. These results indicate broad potential for non-destructive testing and biomedical imaging, as they alleviate pixel-size limitations in photon-counting detectors and sample-size restrictions imposed by optical magnification.