Pump–probe experiments at synchrotrons and free‐electron lasers to study ultrafast dynamics in materials far from equilibrium have been well established, but techniques to investigate equilibrium dynamics on the nano‐ and pico‐second timescales remain underdeveloped and experimentally challenging. A promising approach relies on a double‐probe X‐ray speckle visibility spectroscopy setup at split‐and‐delay beamlines of X‐ray free‐electron lasers. However, the logistics in consistently producing two collinear, perfectly overlapping pulses necessary to conduct a faithful experiment is difficult to achieve. In this paper, a method is introduced to extract contrast in the case where an angular misalignment and imperfect overlap exists between the two pulses. Numerical simulations of a dynamical system show that contrast can still be extracted for significant angular misalignments accompanied by partial overlap between the two pulses.

中文翻译：

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在不完美条件下在X射线散斑可见度光谱实验中提取对比度

在同步加速器和自由电子激光器上进行泵浦探针实验以研究远离平衡的材料中的超快动力学的方法已经很成熟，但是在纳秒和皮秒级时标上研究平衡动力学的技术仍然不发达，并且在实验上具有挑战性。一种有前途的方法依赖于在X射线自由电子激光器的分束和延迟光束线上设置的双探针X射线散斑可见光谱仪。但是，很难连续产生两个忠实实验所需的共线，完全重叠的脉冲的物流。在本文中，介绍了一种在两个脉冲之间存在角度未对准和不完全重叠的情况下提取对比度的方法。