title: A Bragg beam splitter for hard x-ray free-electron lasers.
abstract: We report a Bragg beam splitter developed for utilization of hard x-ray free-electron lasers. The splitter is based on an ultrathin silicon crystal operating in the symmetric Bragg geometry to provide high reflectivity and transmissivity simultaneously. We fabricated frame-shaped Si(511) and (110) crystals with thicknesses below 10 μm by a reactive dry etching method using atmospheric-pressure plasma. The thickness variation over an illuminated area is less than 300 nm peak-to-valley. High crystalline perfection was verified by topographic and diffractometric measurements. The crystal thickness was evaluated from the period of the Pendellösung beats measured with a highly monochromatic and collimated x-ray probe. The crystals provide two replica pulses with uniform wavefront [(<1/50)λ] and low spatial intensity variation (<5%). These Bragg beam splitters will play an important role in innovating XFEL applications.
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1Yamada-oka, Suita, Osaka 565-0871, Japan. osaka@up.prec.eng.osaka-u.ac.jp
authors.forename: Taito
authors.initials: T
authors.lastname: Osaka
authors.forename: Makina
authors.initials: M
authors.lastname: Yabashi
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Sano
authors.forename: Kensuke
authors.initials: K
authors.lastname: Tono
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inubushi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Matsuyama
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yamauchi
mesh_terms: D004583:Electrons; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D012031:Refractometry / Q000295:instrumentation*; D014965:X-Rays