We characterised the displacement of a transmission X-ray tube target parallel to the beam axis due to thermal effects using interferometry. Displacements of up to 10 μm with a sensitivity of about 0.4 μm/W deposited power were measured relative to the X-ray tube's mechanical mounting position. They significantly influence the scale factor of dimensional computed tomography measurements by several 10⁻⁴ at high geometric magnifications. Finite element simulations revealed that the displacement is due to thermal deformation of the entire target assembly and helped to derive a linearised model that predicted the displacements within a few tenths of a micrometre. Radiographic measurements of a calibrated standard confirmed that the mechanical displacement of the target corresponded with the X-ray focal spot position. The findings help to increase the accuracy of dimensional X-ray computed tomography measurements and to ameliorate the design of transmission X-ray tubes.

由于使用干涉测量法的热效应，我们表征了透射 X 射线管目标平行于光束轴的位移。相对于 X 射线管的机械安装位置，以大约 0.4 μm/W 沉积功率的灵敏度测量了高达 10 μm 的位移。它们显着影响三维计算机断层扫描测量的比例因子达 10 ^-4 在高几何放大倍数下。有限元模拟表明，位移是由于整个目标组件的热变形引起的，并有助于推导出线性模型，该模型预测位移在十分之几微米内。校准标准的射线照相测量证实目标的机械位移与 X 射线焦点位置相对应。这些发现有助于提高三维 X 射线计算机断层扫描测量的准确性并改进透射 X 射线管的设计。