Development of Laterally Graded X-Ray Multilayer Optics

Laterally graded multilayer optics play an important role in advanced X-ray applications, enabling precise control of beam properties for spectroscopic and focusing techniques. The Multilayer Deposition System (MDS) at Diamond Light Source (DLS) has demonstrated its ability to fabricate highly precise laterally graded X-ray optics. Developing such optics is challenging due to stringent requirements for precise lateral thickness variations and sagittal uniformity, achieved through optimized substrate speed profiles and advanced mask design. This study presents a comprehensive investigation into the design, fabrication, and characterization of laterally graded multilayers. An adjustable mask design improves sagittal uniformity and reduces optimization times. The structural and optical performance of the multilayers is evaluated, confirming their suitability for synchrotron applications. Two types of laterally graded multilayers were developed: one with a constant lateral gradient (0.005 nm/mm) for O-K edge polarizers, achieving sagittal thickness variations of approximately 0.3–0.4% across an 80 mm substrate, and another featuring a strong variable gradient from 0.037 to 0.112 nm/mm, designed to match the elliptical periodicity profile. The constant gradient multilayer polarizer has been successfully implemented on the state-of-the-art I21 beamline at DLS, highlighting the MDS's role in producing next-generation X-ray optics that meet the stringent demands of synchrotron beamlines.