Analysis of hard x-ray focusing by 2D diamond CRL

X-ray Compound Refractive Lenses (CRLs) made out of diamond have a number of attractive features for applications at modern light sources, such as relatively large refractive index decrement and yet relatively low absorption for hard Xrays, low thermal expansion coefficient and high mechanical rigidity (allowing to safely use them as first optical elements of beamlines), and relatively low undesirable scattering from their volume. However, diamond CRLs are hard to fabricate and process to a (sub-)micron accuracy of the surface shape, required for aberration-free focusing of hard Xrays. We will report on results of experimental tests of first generation 2D diamond CRLs manufactured by Euclid Techlabs LLC. The tests were performed at the Coherent Hard X-ray beamline of the National Synchrotron Light Source II, and included measurements of intensity profiles of ~13 keV undulator radiation focused by one diamond lens in a low-demagnification geometry. Such geometry is typically used for the X-ray beam transport and can be used for the imaging-based diagnostics of the emitting electron beam. The quality of X-ray focusing with the new diamond CRL was analyzed by comparing the measurement results with partially-coherent wave-optics simulations performed with Synchrotron Radiation Workshop code. The tests of the diamond CRL also included measurements of small-angle X-ray scattering produced by it, and comparison of these data with the scattering data from a beryllium CRL with the same focal length.