Single-shot spatial coherence characterization of x-ray ultrafast sources
Résumé
Spatial coherence is an impactful source parameter in many applications ranging from atomic and molecular physics to
metrology or imaging. In lensless imaging, for example, it can strongly affect the image formation, especially when the
source exhibits shot-to-shot variations. Single-shot characterization of the spatial coherence length of a source is thus
crucial. However, current techniques require either parallel intensity measurements or the use of several masks. Based
on the method proposed by González et al. [J. Opt. Soc. Am. A 28, 1107 (2011)], we designed a specific arrangement of a
two-dimensional non-redundant array of apertures, which allows, through its far field interference pattern, for a singleshot measurement of the spatial coherence, while being robust against beam-pointing instabilities. The strategic
configuration of the pinholes allows us to disentangle the degree of spatial coherence from the intensity distribution,
thus removing the need for parallel measurement of the beam intensity. An experimental validation is performed
using a high-harmonic source. A statistical study in different regimes shows the robustness of the method.