Split-and-delay Unit for FEL Interferometry in the XUV Spectral Range
Split-and-delay Unit for FEL Interferometry in the XUV Spectral Range
复制标题
用于 XUV 光谱范围内 FEL 干涉测量的分离延迟单元
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
T. Laarmann
中科院分区：
文献类型：
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作者：
S. Usenko;A. Przystawik;L. L. Lazzarino;M. Jakob;Florian Jacobs;C. Becker;C. Haunhorst;D. Kip;T. Laarmann
在这项工作中，我们提出了一个反射分裂和延迟单元（SDU）的干涉时间分辨实验利用（极紫外）XUV泵浦XUV探测计划与聚焦自由电子激光束。所开发的SDU克服了传统的两个元件分裂镜固有的相位分辨测量的限制，通过一个特殊的设计，使用两个反射层状光栅。光栅产生由每个衍射级中的光栅位移控制的高对比度干涉信号。这些阶在聚焦光学器件的焦平面中分离，这使得能够通过空间选择性地检测两个光场的单个干涉状态来避免相位平均。干涉测量法需要对光场进行精确的相对相位控制，这在短波长下提出了挑战。在我们的设置中，相位延迟由真空中的白色光干涉仪（WLI）确定，该干涉仪以真实的时间监测SDU的表面轮廓，从而测量每个激光发射的延迟。通过光学激光干涉测量法确定，WLI的精度为1 nm。在所提出的实验几何形状，它对应于3作为，这使得相位分辨XUV泵浦XUV探测实验在自由电子激光（FEL）重复率高达60 Hz的时间延迟精度。
In this work we present a reflective split-and-delay unit (SDU) developed for interferometric time-resolved experiments utilizing an (extreme ultraviolet) XUV pump–XUV probe scheme with focused free-electron laser beams. The developed SDU overcomes limitations for phase-resolved measurements inherent to conventional two-element split mirrors by a special design using two reflective lamellar gratings. The gratings produce a high-contrast interference signal controlled by the grating displacement in every diffraction order. The orders are separated in the focal plane of the focusing optics, which enables one to avoid phase averaging by spatially selective detection of a single interference state of the two light fields. Interferometry requires a precise relative phase control of the light fields, which presents a challenge at short wavelengths. In our setup the phase delay is determined by an in-vacuum white light interferometer (WLI) that monitors the surface profile of the SDU in real time and thus measures the delay for each laser shot. The precision of the WLI is 1 nm as determined by optical laser interferometry. In the presented experimental geometry it corresponds to a time delay accuracy of 3 as, which enables phase-resolved XUV pump–XUV probe experiments at free-electron laser (FEL) repetition rates up to 60 Hz.
影响因子：
16.6
作者：
Usenko S;Przystawik A;Jakob MA;Lazzarino LL;Brenner G;Toleikis S;Haunhorst C;Kip D;Laarmann T
通讯作者：
Laarmann T
影响因子：
35
作者：
Ackermann, W.;Asova, G.;Zapfe, K.
通讯作者：
Zapfe, K.