Diffractive and refractive X-ray optics for microanalysis applications

Abstract

A variety of diffractive and refractive X-ray lenses for microfocusing applications at synchrotron beam lines is presented. The devices cover a photon energy range from approximately 250 eV up to 50 keV. For soft X-rays and the multi-keV region, we have fabricated and tested tantalum Fresnel zone plates providing high resolution and good photon efficiency. For photon energies between 10 and 15 keV, linear Fresnel zone plates that can be tuned to excellent efficiencies over a wide energy range are described. For zone plates with binary structures efficiencies up to 26% were measured and test objects with structure widths down to 150 nm could be resolved. Fresnel zone plates with four level structures showed efficiencies up to 65% but the obtained resolution was significantly lower. For hard X-rays with photon energies between 30 and 50 keV, refractive lenses have been manufactured by planar etching of silicon substrates. Diamond planar refractive lenses for 10–20 keV photon energy have been fabricated by a similar technique. The material and geometry make these lenses especially suited to withstand the extreme radiation loads expected in future X-FEL sources.