Development of Wolter Optics for High Resolution Confocal X-ray Fluorescence Imaging

The advent of ultra-bright synchrotron and free-electron laser FEL) x-ray sources means there are new opportunities for novel analytical methods, such as ultrahigh resolution e.g. <250nm) confocal 3D analysis for compositional and chemical state understanding, that could have profound impact on many areas of research. However, to achieve this, capillary optics with substantially improved slope errors are needed to utilize the brightness of the x-ray sources. The proposed project will develop Wolter ellipsoid and hyperboloid) capillary optics that provide superior imaging properties, such as larger numerical aperture and suppressing the focusing of off-axis x-rays. This is advantageous for a wide range of techniques, including for 3D confocal analysis by ensuring only x-rays within a well-defined volume in the sample are collected. Because the proposing company can produce the individual portions ellipsoid and hyperboloid) of the Wolter optic, the Phase I project will evaluate the feasibility of individually producing the components and strategies for aligning them into a Wolter optic. The goal of Phase I is to validate that a Wolter optic with 250nm resolution can be developed. This will be accomplished by extending the proposing company’s existing ray tracing program and then using the program to analyze 1) tolerances for aligning individual hyperboloid and ellipsoid optics and 2) tolerances for surface figure errors of both individual components required to achieve 250nm resolution. Information from these tasks will then be used to determine the feasibility of designing and implementing an electromechanical system for aligning the components. The Wolter capillary lenses developed in this proposal will be commercialized as components for x-ray beamlines. Sigray has already commercialized paraboloidal and ellipsoidal optics and received over $1.3M in purchase orders from synchrotron customers worldwide, and the Wolter optics proposed would be of significant commercial value. In addition, the optics will be used as a key component in many of the proposing company’s suite of laboratory x-ray systems. Wolter optics offer ideal properties as x-ray imaging optics and will be particularly valuable for the company’s x-ray fluorescence and x-ray microscopy products.