Structured X-Ray Optics for Laboratory-Based Materials Analysis

Metamaterials provide a challenge for materials analysis, as large-scale 3D geometries confound traditional methods. X-ray optics that allow for novel beam geometries and for more efficient use of conventional X-ray sources can be important in defect and structure analysis to close the loop between design and performance. Fortunately, metamaterials have also provided a new variety of array and structured X-ray optics. Because X-rays barely interact with materials, their index of refraction in any material is only slightly different from unity, so it is very difficult to make the sort of refractive optics that are used for visible light. Instead, diffraction can be used to control the direction or wavelength of X-rays. Structured diffractive optics include transmission gratings, artificial multilayers, and arrays of curved crystals. X-rays also have very high reflectivity at grazing incidence. This phenomenon allows for reflective arrays such as multipore and polycapillary optics.