Influence of optics vibration on synchrotron beam coherence.

Vibration of optics is one of the major limiting factors of the performance of state-of-the-art beamlines at low-emittance synchrotron facilities. We present a theoretical model with experimental data describing vibration-induced effects on x-ray beam coherence. Owing to the incoherent nature of vibration, the decrease in the beam spatial coherence perturbed by optics vibrations can be characterized by modeling the effective source profile of the vibrating beam. The measurements were carried out by using grating interferometry and a refractive lens with controlled vibration as test optics. The experimental results confirm the model and reveal the dependency of the measured beam spatial coherence on the acquisition time. The proposed method can be used to identify the eigenfrequency of the optical system as well as to optimize beamline operation and experimental conditions for coherence-related techniques.