Experimental determination of the diffraction efficiency and high-order suppression of gratings for synchrotron radiation
Experimental determination of the diffraction efficiency and high-order suppression of gratings for synchrotron radiation
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DOI：
10.1117/12.279368
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发表时间：
1997-11
期刊：
影响因子：
--
通讯作者：
U. Flechsig;F. Eggenstein;R. Follath;F. Senf
中科院分区：
文献类型：
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作者：
U. Flechsig;F. Eggenstein;R. Follath;F. Senf
我们提出了新的实验数据衍射效率测量光栅的第一波荡器光束线在BESSY II。测量数据将与电磁理论的结果进行比较。在BESSY II的光束线设计过程中，对高阶的良好抑制，即从较高能量衍射到与第一阶相同的角度的高阶的总和，一直是一个重要的问题。为此目的，层状光栅结构已被优化和指定。用三轴真空衍射仪在BESSY I PM 4光束线处在70至1200 eV的能量范围内进行测量。我们测量了离散能量E处的一阶以及相应的二阶和三阶衍射效率，即分别在2 E和3 E处的二阶和三阶效率。为了提高测量的准确性，必须考虑PM 4光束线的高阶。我们使用的计算方案开始在最高的能量，其中的衍射效率的测试下的光栅和更高的订单从单色器已被同时评估。然后将计算出的单色仪的更高阶数递归用作较低能量下计算的输入。在不同的角度设置下测量光栅，因此能够实现不同程度的高阶抑制。已确定，通过适当的角度设置，可以显著减少单色光栅的高阶。
We present new experimental data on diffraction efficiency measurements on gratings for the first undulator beamlines at BESSY II. The measured data will be compared with results from electromagnetic theory. A good suppression of higher orders, i.e. the sum of higher orders from higher energies which are diffracted into the same angle as the first order, has been an important point during the design process of the beamlines at BESSY II. For this purpose lamellar grating structures have been optimized and specified. The measurements were carried out with a triple axis vacuum diffractometer at the BESSY I PM 4 beamline in an energy range from 70 to 1200 eV. We measured the diffraction efficiencies of the first order and the corresponding second and third order at discrete energies E, i.e. second and third order efficiency at 2E and 3E respectively. To improve the accuracy of the measurements, the higher orders from the PM 4 beamline had to be taken into account. We used a calculation scheme starting at the highest energy, in which the diffraction efficiency of the grating under test and the higher orders from the monochromator have been evaluated simultaneously. The calculated higher orders of the monochromator were then recursively used as input for the calculation at lower energies. The gratings were measured at different angular settings, hence enabling different degrees of high order suppression. It was determined, that with appropriate angular settings, the higher orders of monochromator gratings can be significantly reduced.