Spatial coherence properties of a compact and ultrafast laser-produced plasma keV x-ray source

The authors use Fresnel diffraction from knife-edges to demonstrate the spatial coherence of a tabletop ultrafast x-ray source produced by laser-plasma interaction. Spatial coherence is achieved in the far field by producing micrometer-scale x-ray spot dimensions. The results show an x-ray source size of $6\mu \mathrm{m}$ that leads to a transversal coherence length of $20\mu \mathrm{m}$ at a distance of $60\mathrm{cm}$ from the source. Moreover, they show that the source size is limited by the spatial spread of the absorbed laser energy.