Multilayer optics for synchrotron applications

X-ray multilayer optics play a vital role in synchrotron optics due to their ability to generate constructive interference. These devices typically consist of several tens to hundreds of periods of alternating layers coated on a substrate. In contrast to single-layer mirrors that reflect X-rays within a specific energy range, multilayer optics can be tailored to achieve a high reflection over a broad energy spectrum. This is a sought-after property for many beamlines and has led to the development of numerous new X-ray applications and capabilities. This review highlights advances in multilayer optics, including fabrication techniques, layer structure design, material choice, and strategies to enhance performance. This is placed in the context of recent applications of such multilayers as monochromator and gratings, focusing devices, and polarizers. Current challenges and the future outlook within this field are also proposed. This comprehensive summary of a rapidly advancing field highlights recent achievements and is intended to promote practical applications in terms of the use of multilayer synchrotron optics.