Multilayer Laue Lenses for Enhanced Spatial Resolution in Dark-Field X-ray Microscopy

TL;DR

This paper demonstrates the use of Multilayer Laue Lenses as objectives in Dark-Field X-ray Microscopy, achieving significantly improved spatial resolution and efficiency over traditional lenses, enabling advanced imaging applications.

Contribution

The study introduces a novel application of crossed MLLs in DFXM, achieving over three times better resolution and larger numerical aperture compared to conventional CRL objectives.

Findings

Achieved 56 nm spatial resolution in bright-field mode.

MLL objective has an efficiency of 26.7%.

NA of MLL is three times larger than CRL, enabling faster mapping.

Abstract

We introduce the use of a crossed pair of Multilayer Laue Lenses (MLLs) as an objective in Dark-Field X-ray Microscopy (DFXM). In a demonstration experiment at the ID03 beamline at ESRF, two flat Mo-Si MLLs were used, with a physical aperture of 50 x 50 $\mathrm{\mu m^2}$ and a focal length of 14.25 mm at 19 keV. Applying a 10 % criterion to the Modulation Transfer Functions (MTFs) acquired, a spatial resolution of 56 nm is obtained in bright-field mode -- more than three times better than with a compound refractive lens (CRL) objective. The dark-field resolution is similar. With an efficiency of 26.7 % the MLL objective expands the science domain of DFXM significantly, both for bulk and near-surface studies. Similar to the CRL case, the reciprocal space resolution is dominated by the numerical aperture (NA) of the objective, with the NA being three times larger in the MLL case. This enables faster orientation mapping and implies improved options for the use of tomographic reconstruction algorithms. Although the MLL objective pupil varies with energy and position, secondary peaks are suppressed, simplifying both interpretation and forward simulations. We present an example DFXM application using the MLL as an objective, imaging a through-silicon via Kelvin device.