Nanometer-resolution hard X-ray near-field ptychography with multilayer Laue lenses

In coherent X-ray diffraction imaging, resolution is limited by the scattering power of the sample, where high-angle signals are weak and compete with background and noise. In this work, we analyzed and experimentally demonstrated that hard X-ray projection imaging with high numerical aperture multilayer Laue lenses achieves improved resolution by adding a strong reference wave to boost the signal against background and noise. Combined with transversely scanning the sample, robust phase retrieval reconstruction is carried out through the modality of near-field ptychography. We demonstrated this at a photon energy of 17.4 keV, using lenses of 0.014 NA, by achieving images of a Siemens star test object and a hierarchical nanoporous gold sample at a spatial resolution below 10 nm.