Marathe Shashidhara, Shi Xianbo, Wojcik Michael J, Kujala Naresh G, Divan Ralu, Mancini Derrick C, Macrander Albert T, Assoufid Lahsen
Opt Express. 2014 Jun 16;22(12):14041-53. doi: 10.1364/OE.22.014041.
Transverse coherence of the x-ray beam from a bending magnet source was studied along multiple directions using a 2-D π/2 phase grating by measuring interferogram visibilities at different distances behind the grating. These measurements suggest that the preferred measuring orientation of a 2-D checkerboard grating is along the diagonal directions of the square blocks, where the interferograms have higher visibility and are not sensitive to the deviation of the duty cycle of the grating period. These observations are verified by thorough wavefront propagation simulations. The accuracy of the measured coherence values was also validated by the simulation and analytical results obtained from the source parameters. In addition, capability of the technique in probing spatially resolved local transverse coherence is demonstrated.
利用二维π/2相位光栅，通过测量光栅后不同距离处的干涉图可见度，沿多个方向研究了来自弯曲磁铁源的X射线束的横向相干性。这些测量结果表明，二维棋盘格光栅的首选测量方向是沿着方形块的对角线方向，在该方向上干涉图具有更高的可见度，并且对光栅周期占空比的偏差不敏感。这些观察结果通过全面的波前传播模拟得到了验证。测量相干值的准确性也通过从源参数获得的模拟和分析结果得到了验证。此外，还展示了该技术探测空间分辨局部横向相干性的能力。
