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.

Status of the SACLA Facility

“…We developed a hard X-ray split-and-delay optical (SDO) system based on the Bragg diffraction in crystal optics for generating two split pulses with a variable temporal separation [46][47][48]. To achieve both high stability and operational flexibility, the SDO system was designed to include both variable-delay and fixed-delay branches.…”

X-Ray Near-Field Holography: Beyond Idealized Assumptions of the Probe

“…In the case of parallel recording as required for single pulse FEL imaging, a semi-transparent detector screen in front of the object (denoted by detector 2 in Fig. 5.1) could be used, or a beam splitter in front of O to split the XFEL pulse before it interacts with O [146,147].…”

Demonstration of simultaneous experiments using thin crystal multiplexing at the Linac Coherent Light Source

“…Manufacturing such a thin specimen while maintaining lattice perfection and having it mounted free of strain can be very challenging despite much concerted effort by many (Feng et al, 2012b;Osaka et al, 2012). More importantly, it was observed that a thin Si membrane sample would exhibit significant vibrations and thus local bending when exposed to an unattenuated X-ray FEL beam at a typical energy of a few mJ pulse À1 (Feng et al, 2012b(Feng et al, , 2013b.…”