An achromatic X-ray lens

Adam Kubec,Ana Diaz,Umut T Sanli,Marie-Christine Zdora,Christian David,Joan Vila-Comamala

doi:10.1038/s41467-022-28902-8

Adam Kubec, Ana Diaz + Show 4 more

Open Access

https://doi.org/10.1038/s41467-022-28902-8

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Abstract

Diffractive and refractive optical elements have become an integral part of most high-resolution X-ray microscopes. However, they suffer from inherent chromatic aberration. This has to date restricted their use to narrow-bandwidth radiation, essentially limiting such high-resolution X-ray microscopes to high-brightness synchrotron sources. Similar to visible light optics, one way to tackle chromatic aberration is by combining a focusing and a defocusing optic with different dispersive powers. Here, we present the first successful experimental realisation of an X-ray achromat, consisting of a focusing diffractive Fresnel zone plate (FZP) and a defocusing refractive lens (RL). Using scanning transmission X-ray microscopy (STXM) and ptychography, we demonstrate sub-micrometre achromatic focusing over a wide energy range without any focal adjustment. This type of X-ray achromat will overcome previous limitations set by the chromatic aberration of diffractive and refractive optics and paves the way for new applications in spectroscopy and microscopy at broadband X-ray tube sources.

Highlights

Diffractive and refractive optical elements have become an integral part of most highresolution X-ray microscopes
Reflective X-ray optics rely on grazing incidence configuration and require complicated geometries to produce a magnified image of an extended field of view[4,5], resulting in long focal lengths that are incompatible with a compact setup. While these limitations do not apply to refractive and diffractive optics, making them more suitable for the formation of magnified X-ray images, they suffer from inherent chromatic aberration, meaning that X-rays of different energies are not focused to the same focal plane
The presented X-ray achromat consisted of a Fresnel zone plate (FZP) fabricated using electron-beam lithography and nickel electroplating and a 3D-printed refractive lens (RL) made by two-photon polymerisation

Summary

Introduction

Diffractive and refractive optical elements have become an integral part of most highresolution X-ray microscopes. Using scanning transmission X-ray microscopy (STXM) and ptychography, we demonstrate sub-micrometre achromatic focusing over a wide energy range without any focal adjustment This type of X-ray achromat will overcome previous limitations set by the chromatic aberration of diffractive and refractive optics and paves the way for new applications in spectroscopy and microscopy at broadband X-ray tube sources. Reflective X-ray optics rely on grazing incidence configuration and require complicated geometries to produce a magnified image of an extended field of view[4,5], resulting in long focal lengths that are incompatible with a compact setup While these limitations do not apply to refractive and diffractive optics, making them more suitable for the formation of magnified X-ray images, they suffer from inherent chromatic aberration, meaning that X-rays of different energies are not focused to the same focal plane. 2π 1 2 where (1 − δ) and β are the real and imaginary parts of n, λ is the

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