Modelling phase imperfections in compound refractive lenses

TL;DR

This paper presents a physical-optics simulation framework to analyze the impact of phase imperfections in compound refractive lenses on X-ray beam focusing, aiding the design of aberration-free high-resolution optics.

Contribution

It introduces a multi-level modeling approach incorporating measured phase errors and optical imperfections to improve CRL performance predictions.

Findings

Phase errors significantly affect CRL focusing quality.

The models validate design equations and figures of merit.

Simulations guide optimization of lens fabrication and alignment.

Abstract

Compound refractive lenses (CRL) offer outstanding potential for probe formation in X-ray micro- and nano-analysis as well as for imaging applications, but effective aberration-free focusing of X-rays is a key consideration when high spatial resolution and intensities are required. Available refractive optics have non-negligible aberrations which degrade their final performance. We describe a framework based on physical-optics for simulating the effect of imperfect CRL upon an X-ray beam, taking into account measured phase errors obtained from at-wavelength metrology. We model, with increasing complexity, a CRL stack as a single thin phase element, then as a more realistic compound-element including absorption and thickness effects and finally, we add realistic optical imperfections to the CRL. Coherent and partially-coherent simulations using the "Synchrotron Radiation Workshop" (SRW) are used to evaluate the different models, the effects of the phase errors and to check the validity of the design equations and suitability of the figures of merit.