Hard x-ray holographic nanoimaging using multilayer Laue lenses

We present an approach to hard x-ray holographic projection microscopy that combines the use of high numerical aperture multilayer Laue lenses (MLLs) with high-Z single-photon-counting detection. Unlike conventional Kirkpatrick–Baez mirror-based systems, MLLs provide higher numerical apertures at high photon energies. This enables photon-noise-limited detection of high-resolution propagation-based phase-contrast images, while avoiding excessively long propagation distances and relaxing constraints on source size and source-to-MLLs distance. These features make the approach well suited to high-resolution studies of radiation-sensitive specimens and strongly absorbing samples. The first implementation at PETRA III achieved a spatial resolution of 50 nm at 30 keV. However, as high phase sensitivity renders the technique susceptible to optical aberrations, we characterize and compare the aberrational effects of flat and wedged MLLs by measuring their wavefronts and the resulting phase-contrast images. We demonstrate the resolution and image quality by experiments on 2D test patterns and potential applications through rapid 3D holotomography measurements of alloys and soft materials.