Specially Designed Multilayers

Abstract

Periodic multilayers, utilising Bragg reflection at single angle or wavelength, are established as efficient reflectors from the hard X-ray down to the extreme ultraviolet (XUV) region of the electromagnetic spectrum. More recently, both laterally and depth-graded multilayers have been designed and fabricated; they allow either reflection of divergent beams or over a broad angular or wavelength range, or a combination of both. Recent developments in aperiodic structures, along with advances in ultra-short period and transmission mutilayers, are discussed in this chapter. Modelling methods to provide designs for specific purposes are described, as are advances in manufacturing techniques and quality control. In addition to peak reflectivity at a specific wavelength or angle, high integrated reflectivity over a given wavelength or angular range is considered, along with flat reflectivity profiles. Important potential applications of flat response mirrors are X-ray micro-spectroscopy, X-ray diffraction, XUV polarimetry, and any other technique requiring both high reflectivity and broad bandwidth.