The past decade has witnessed tremendous growth in both interest and available techniques for laboratory X-ray analysis. From the progression of commercially-available micro- and nano-CT scanners to the resolution and sensitivity enhancements of x-ray fluorescence spectrometers, the scientific community is benefiting from a rapid expansion of laboratory-based x-ray techniques.
In our work, we have developed a suite of advanced x-ray instrumentation providing a wide range of enhanced capabilities for specimen characterization. The key enabling technology lies in the X-ray source, which features a microstructured target capable of providing 5-10x higher brightness than conventional sealed-tube x-ray sources and offering power flux densities that rival rotating anode sources. The target array can be custom-designed to incorporate a variety of materials, facilitating fast & easy switching between characteristic emission lines and radiation spectra. This source has been subsequently integrated with state-of-the-art X-ray focusing optics, such as ellipsoidal/paraboloidal capillary lenses and finely-structured Fresnel zone plate imaging objective lenses, and sensitive scintillator-coupled CCD detection systems, opening up new opportunities for advancing laboratory x-ray inspection equipment.
Here, we will describe the system geometries in detail and demonstrate how these new advancements have led us to the development of laboratory micro-XRF, nano-XRM, and XAS instrumentation. We will also briefly introduce the image-centric software workspace, which facilitates novice users to collect data quickly and reliably with minimal training overhead.
Sigray’s axially symmetric x-ray optics enable advanced microanalytical capabilities for focusing x-rays to microns-scale to submicron spot sizes, which can potentially unlock many avenues for laboratory micro-analysis. The design of these optics allows submicron spot sizes even at low x-ray energies, enabling research into low atomic number elements and allows increased sensitivity of grazing incidence measurements and surface analysis. We will discuss advances made in the fabrication of these double paraboloidal mirror lenses designed for use in laboratory x-ray applications. We will additionally present results from as-built paraboloids, including surface figure error and focal spot size achieved to-date.
An absolute efficiency measurement technique for Fresnel zone plates using an electron impact micro-focus laboratory
X-ray source (Lα line of Tungsten at 8.4 KeV) is demonstrated. A quasi-monochromatic x-ray image of a zone plate was
obtained employing a pair of copper and cobalt filters. Applying this method to zone plates optimizes the zone plate
fabrication process and provides the ability to explore zone geometry to achieve the best possible efficiency. Several
zone plate parameters were tested with first order efficiency measuring from 1% to 29%.
Two-dimensional multilayer optics have been widely used for enhancing and monochromatizing x-ray beams for various diffraction applications. However, when they are applied to Mo Kα radiation, the performance suffers from the fact that multilayer optics can use only a very small portion of the source. This is because the rocking curve of a multilayer becomes narrower at higher energy. Comparing to the optics for the Cu Kα radiation, the throughput of the optics for Mo Kα depends heavily on how small the source is. Based on the theoretical ray-tracing study, we have designed, fabricated and tested a system combining a microfocusing x-ray source and a side-by-side multilayer optic. Initial test results agree well with the theoretical expectation. The flux gain for a sample smaller than 100 micrometers is about 9 fold compared to a system composing of 2 kW sealed tube and graphite monochromator. The resolution of a diffractometer can also be improved by configuring the optical path. This paper will discuss the system design, detailed comparison between this system and a sealed tube-graphite monochromator based system, and possible applications such as small molecule diffraction system. A theoretical comparison to a rotating anode based system will also be discussed.