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Characterising the large coherence length at diamond’s beamline I13L

DOI: 10.1063/1.4952942 DOI Help

Authors: U. H. Wagner (Diamond Light Source) , A. Parsons (Diamond Light Source) , J. Rahomaki (KTH Royal Institute of Technology) , U. Vogt (KTH Royal Institute of Technology) , C. Rau (Diamond Light Source; Northwestern University)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: Proceedings of the 12th International Conference on Synchrotron Radiation Instrumentation – SRI2015
Peer Reviewed: No

State: Published (Approved)
Published: July 2016

Abstract: I13 is a 250 m long hard x-ray beamline (6 keV to 35 keV) at the Diamond Light Source. The beamline comprises of two independent experimental endstations: one for imaging in direct space using x-ray microscopy and one for imaging in reciprocal space using coherent diffraction based imaging techniques [1]. An outstanding feature of the coherence branch, due to its length and a new generation of ultra-stable beamline instrumentation [2], is its capability of delivering a very large coherence length well beyond 200 μm, providing opportunities for unique x-ray optical experiments. In this paper we discuss the challenges of measuring a large coherence length and present quantitative measurement based on analyzing diffraction patterns from a boron fiber [3]. We also discuss the limitations of this classical method in respect to detector performance, very short and long coherence lengths. Furthermore we demonstrate how a Ronchi grating setup [4] can be used to quickly establish if the beam is coherent over a large area.

Journal Keywords: Coherence; Coherence imaging; Optical fiber testing; X-ray diffraction; Optical coherence

Subject Areas: Physics

Technical Areas: Insertion Devices