Physical-optics simulation of PSD-driven wavefront degradation in x-ray mirrors

Abstract

As synchrotron and FEL sources become more brilliant and coherent, wave‑optics effects increasingly limit beamline performance. We model x‑ray propagation through mirrors, slits, and gratings in grazing‑incidence geometries, quantifying how diffraction, scattering, partial coherence, surface figure and microroughness, and thermal deformations affect wavefront quality and focal spot size. Surface spatial frequencies are described by the Power Spectral Density (PSD), derived from metrology (interferometry, profilometry, AFM) and treated as the squared modulus of the surface‑profile Fourier transform (or the Fourier transform of the autocovariance). Physical‑optics simulations link PSD bands to Point Spread Function degradation from EUV to hard x‑rays and show how diffraction‑ and scattering‑driven contributions vary with photon energy and incidence angle. We present an updated WISE implementation in the OKONA propagator within the OASYS framework, enabling partially coherent sources and realistic full‑length mirror profiles consistent with measured statistics. This workflow supports sensitivity studies, specification setting, and targeted mitigation where aberrations are critical.