Partially coherent simulations supporting development and use of nanofocusing x-ray optics

Abstract

The Synchrotron Radiation Workshop code enables high-fidelity physical-optics simulations through detailed electrodynamics-based modeling of synchrotron radiation sources and simulation of radiation propagation through optical systems. Such simulations are instrumental for the development and adoption of nanofocusing x-ray optics at next-generation synchrotron facilities. In this study we demonstrate how SRW’s partially coherent calculation capability was applied to predict, plan, and validate a new Kirkpatrick-Baez mirror system designed for high throughput at the Hard x-ray Nanoprobe beamline of NSLS-II. Simulations incorporating source optics parameters forecast intensity distributions and coherence lengths across the secondary-source-aperture size, determining the diffraction-limited focusing conditions and informing data-collection planning. During beamtime, KB alignment was guided by imaging of known targets and the directions of focal sidelobes; the beam position on the KB aperture was subsequently quantified against SRW far-field predictions. The far-field comparison also provides an in-situ test of the applied mirror figure error, confirming that the ptychographically reconstructed figure error amplitude is consistent with other measurements. The partially coherent simulation (36 × 77nm,H × V) reproduced the focal spot measured in-situ by ptychography in the companion study (33 × 71nm), demonstrating the accuracy and utility of these simulations and their value for coherence-preserving beamline design, optics characterization, and real-time experiment steering.