Implementation of a crossed‐slit system for fast alignment of sealed polycapillary X‐ray optics.

A new modification of a table‐top laser‐driven water‐jet plasma X‐ray source has been successfully implemented and commissioned at the Extreme Light Infrastructure (ELI) Beamlines user facility. In order to preserve the broadband nature of the source for spectroscopic experiments, a polycapillary lens was initially chosen as the focusing element. Generally, polycapillary X‐ray optics have a narrow photon acceptance angle and small field of view, making alignment complicated and time‐consuming. This contribution demonstrates a straightforward, reliable and reproducible procedure for aligning polycapillary focusing optics with broadband X‐rays. The method involves a pre‐alignment step where two X‐ray slits are mounted orthogonally on opposite sides of a 3D‐printed cylindrical polycapillary holder. This helps to precisely determine the optical axis of the X‐ray beam. Subsequent mounting of the polycapillary in the pre‐aligned holder with the slits removed allowed for immediate transmission of the X‐ray photons through the optics and has provided a good starting point for fine alignment. [ABSTRACT FROM AUTHOR]