Systematic understanding and real-time feedback capability for x-ray free electron laser (FEL) accelerator and optical components are critical for scientific experiments and instrument performance. Single-shot wavefront sensing enables characterization of the intensity and local electric field distribution at the sample plane, something that is important for understanding scientific experiments such as nonlinear studies. It can also provide feedback for alignment and tuning of the FEL beam and instrumentation optics, leading to optimal instrument performance and greater operational efficiency. A robust, sensitive, and accurate single-shot wavefront sensor for x-ray FEL beams using single grating Talbot interferometry has been developed. Experiments performed at the Linac Coherent Light Source (LCLS) demonstrate $3\sigma$ sensitivity and accuracy, both better than $\lambda /100$, and retrieval of hard x-ray ($\lambda =0.13\mathrm{nm}$, $E=9.5\mathrm{keV}$) wavefronts in 3D. Exhibiting high performance from both unfocused and focused beams, the same setup can be used to systematically study the wavefront from the FEL output, beam transport optics, and endstation focusing optics. This technique can be extended for use with softer and harder x rays with modified grating configurations.

中文翻译：

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用于X射线自由电子激光器的高精度波前感测

对X射线自由电子激光（FEL）加速器和光学组件的系统了解和实时反馈功能对于科学实验和仪器性能至关重要。单发波前感测可以表征样品平面上的强度和局部电场分布，这对于理解科学实验（例如非线性研究）非常重要。它还可以为FEL光束和仪器光学器件的对准和调谐提供反馈，从而获得最佳的仪器性能和更高的工作效率。已经开发出了使用单光栅Talbot干涉术的用于X射线FEL光束的稳健，灵敏，准确的单脉冲波前传感器。在直线加速器相干光源（LCLS）上进行的实验表明$3\sigma$ 灵敏度和准确性均优于 $\lambda /100$，以及获取硬X射线（$\lambda =0.13\mathrm{纳米}$， $E=9.5\mathrm{keV}$）的3D波阵面。为了展示未聚焦和聚焦光束的高性能，可以使用相同的设置从FEL输出，光束传输光学器件和终端站聚焦光学器件系统地研究波前。可以扩展此技术，以用于具有修改后的光栅配置的软X射线和硬X射线。