Focusing optics for soft and hard X -rays: Fabrication, replication and simulations

X rays are powerful probes for study of a variety of samples at the nanoscale. While spot sizes of <50 nm are possible, the resolution is ultimately limited by the optics. Unfortunately, x-ray optics are difficult to fabricate, which limits their overall availability. We investigated various methods aimed at improving the availability of x-ray lenses while maintaining the highest quality.;Zone plates are the focusing element in most x-ray microscopes with a resolution that is limited by the outermost zone width, i.e. the smallest feature, and an efficiency that is determined by the zone material and thickness. Electron beam lithography (EBL) was used to meet the fabrication demands for high quality zone plates. We developed new processes to cut writing and processing time while maintaining high resolution and efficiency. By fabricating large diameter zone plates without field stitching errors, we have made it possible to study wet specimens at the carbon edge with higher resolution than was available previously. These new processes were enabled by a new e-beam tool, which required us to update existing processes and custom software.;Regardless of process streamlining, fabrication with EBL yields a small number of useful optics. We investigated step-and-flash lithography as a possible new direction for replicating zone plates to increase their worldwide availability. We took the initial steps towards replication and proposed a procedure for fabrication by this method.;The availability of high-resolution, high-efficiency optics for hard x-rays is limited by high aspect ratio requirements. We developed processes to fabricate Bragg-Fresnel zone plates and Fresnel lenses in deep-etched silicon for use in this energy range.;Since the resolution of zone plates is linked to the smallest feature size, limited access to state-of-the-art lithography tools limits the overall availability of the highest resolution optics. Recent publications described photon sieves as a possible alternative to zone plates since their resolution limit is independent of a lithography limit. We performed computer simulations comparing photon sieves and compound zone plates showing that the zone plates provide equal gains in resolution for a given lithography limit while performing with superior efficiencies.