Characterizing the inner surface of parabolic monocapillary with contrast-enhanced micro-CT technology and ray-tracing computing method

Accurately characterizing the inner surface of monocapillary X-ray optics is important because the deformation of the inner wall is the greatest limitation on the quality of monocapillaries. Here, a contrast-enhanced microscopic computed tomography (micro-CT) technology was applied to measure the monocapillary. The 50 nm lead powder was used to fill the hollow part of a parabolic monocapillary X-ray optics (PMXO). The relative percentage of the hollow filled with lead powder versus the glass wall in grey values was about 6.92 times as much as that of the original PMXO, which is greatly conducive to CT reconstruction. In order to study the effect of inner radius error on the performance, a fitting cubic spline curve based on measured radius data was regarded as the inner profile to establish the mathematical model of actual PMXO. Then, a numerical calculation based on the ray-tracing method was used to simulate X-ray intensity distribution, transmission efficiency and divergence for the actual and designed (the parabolic equation parameter p=0.001083793 mm) PMXOs, respectively. This methodology provides the potential for application in the 3D measurement and the quality assessment of the inner surface of monocapillary X-ray optics.