X-ray focusing and optics

Abstract

This chapter addresses fundamental concepts of X-ray optics and X-ray coherence, in view of the increasing number of X-ray applications requiring nano-focused X-ray beams. The chapter is meant as a tutorial to facilitate the understanding of later chapters of this book. After the introduction and an overview over focusing optics and recent benchmarks in X-ray focusing, we present refractive, reflective and diffractive X-ray optics in more detail. Particular emphasis is given to two kinds of X-ray optics which are particularly relevant for later chapters in this book, namely X-ray waveguides (XWG) and multilayer zone plates (MZP). Both are geared towards ultimate confinement and focusing, respectively, i.e. applications at the forefront of what is currently possible for multi-keV radiation. Since optics must be designed in view of coherence properties, we include a basic treatment of coherence theory and simulation for X-ray optics. Finally, the chapter closes with a brief outlook on compound (combined) optical schemes for hard X-ray microscopy.