Direct measurement of scattering signals

“Dark-field” (or Ultra-small angle scattering) measurements with the edge-illumination (EI) method are connected to the general theory of x-ray scattering, showing EI allows absolute measurement of the scattering signals with no influence from the characteristics of the imaging system (e.g. auto-correlation length). An additional contrast channel is also introduced – the variance of refraction – that plays an analogous role as dark field for sample features larger than the system’s spatial resolution. 

Modelling of the scattering distribution from an ensemble of microspheres, when multiple scattering is and is not negligible (left and right hand panels, respectively). The article shows how this model is compatible both with the classic theory of x-ray scattering and with the experimental measurements performed with EI.