Liu Yanwei, Seaberg Matthew, Feng Yiping, Li Kenan, Ding Yuantao, Marcus Gabriel, Fritz David, Shi Xianbo, Grizolli Walan, Assoufid Lahsen, Walter Peter, Sakdinawat Anne
SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439, USA.
J Synchrotron Radiat. 2020 Mar 1;27(Pt 2):254-261. doi: 10.1107/S1600577519017107. Epub 2020 Feb 12.
Wavefront sensing at X-ray free-electron lasers is important for quantitatively understanding the fundamental properties of the laser, for aligning X-ray instruments and for conducting scientific experimental analysis. A fractional Talbot wavefront sensor has been developed. This wavefront sensor enables measurements over a wide range of energies, as is common on X-ray instruments, with simplified mechanical requirements and is compatible with the high average power pulses expected in upcoming X-ray free-electron laser upgrades. Single-shot measurements were performed at 500 eV, 1000 eV and 1500 eV at the Linac Coherent Light Source. These measurements were applied to study both mirror alignment and the effects of undulator tapering schemes on source properties. The beamline focal plane position was tracked to an uncertainty of 0.12 mm, and the source location for various undulator tapering schemes to an uncertainty of 1 m, demonstrating excellent sensitivity. These findings pave the way to use the fractional Talbot wavefront sensor as a routine, robust and sensitive tool at X-ray free-electron lasers as well as other high-brightness X-ray sources.
在X射线自由电子激光器上进行波前传感对于定量理解激光器的基本特性、对准X射线仪器以及进行科学实验分析至关重要。一种分数塔尔博特波前传感器已被开发出来。这种波前传感器能够在很宽的能量范围内进行测量，这在X射线仪器中很常见，其机械要求简化，并且与即将到来的X射线自由电子激光器升级中预期的高平均功率脉冲兼容。在直线加速器相干光源上分别在500 eV、1000 eV和1500 eV能量下进行了单次测量。这些测量被用于研究反射镜对准以及波荡器渐变方案对光源特性的影响。束线焦平面位置的跟踪精度达到了0.12 mm的不确定度，各种波荡器渐变方案下光源位置的跟踪精度达到了1 m的不确定度，显示出了出色的灵敏度。这些发现为将分数塔尔博特波前传感器用作X射线自由电子激光器以及其他高亮度X射线源的常规、稳健且灵敏的工具铺平了道路。
