Nagler Bob, Galtier Eric C, Brown Shaughnessy B, Heimann Philip, Dyer Gilliss, Lee Hae Ja
SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
J Synchrotron Radiat. 2020 Nov 1;27(Pt 6):1461-1469. doi: 10.1107/S1600577520010735. Epub 2020 Sep 14.
Ronchi testing of a focused electromagnetic wave has in the last few years been used extensively at X-ray free-electron laser (FEL) facilities to qualitatively evaluate the wavefront of the beam. It is a quick and straightforward test, is easy to interpret on the fly, and can be used to align phase plates that correct the focus of aberrated beams. In general, a single Ronchigram is not sufficient to gain complete quantitative knowledge of the wavefront. However the compound refractive lenses that are commonly used at X-ray FELs exhibit a strong circular symmetry in their aberration, and this can be exploited. Here, a simple algorithm that uses a single recorded Ronchigram to recover the full wavefront of a nano-focused beam, assuming circular symmetry, is presented, and applied to experimental measurements at the Matter in Extreme Conditions instrument at the Linac Coherent Light Source.
在过去几年中，聚焦电磁波的龙奇测试已在X射线自由电子激光（FEL）设施中广泛用于定性评估光束的波前。这是一种快速且直接的测试，易于即时解读，并且可用于对准校正像差光束焦点的相位板。一般来说，单张龙奇图不足以全面定量了解波前。然而，X射线自由电子激光中常用的复合折射透镜在其像差方面呈现出很强的圆对称性，这一点可以加以利用。在此，提出了一种简单算法，该算法利用单张记录的龙奇图，在假设圆对称的情况下恢复纳米聚焦光束的完整波前，并将其应用于直线加速器相干光源极端条件物质仪器的实验测量中。
