Annular x-ray optics offer improved resolution for radiation sensitive samples

Abstract To detect faint signals from weakly scattering samples, high-resolution x-ray microscopy typically requires a high photon flux. This exposes samples to high radiation doses and can cause radiation damage. In this work we propose the use of annular optics in scanning microscopy as an alternative to full-aperture optics. Annular optics act as high-pass filters that produce a stronger signal from edges. Compared to regular optics with the same numerical aperture, annular optics expose the sample to less dose while producing the same signal from small sample features. Annular optics benefit significantly from the high photon fluxes of the latest x-ray sources to compensate for their overall smaller cross section. Using numerical simulations, we show that annular optics offer superior optical performance for sample features close to the resolution limit of the optic.