第三代同步辐射光源X射线相干性测量研究

随着高性能第三代同步辐射光源的建成开放,基于X射线相干特性的实验方法得到了快速发展和广泛应用.作为一个典型的例子,X射线相位衬度成像已经成为常规的X射线实验方法并向用户开放.相干散射、相干衍射成像、光子关联谱等X射线实验方法正日益受到重视,在高空间分辨、时间分辨等研究领域已显示出其独特的优越性.因此,研究和测量第三代同步辐射的空间相干特性对进一步发展这些新的实验方法具有重要意义.基于Talbot自成像原理成功测量了上海光源X射线成像线站发射的X射线的空间相干长度,并进而测得了相应光源的空间尺度.光子能量为33.2 keV时,测得的X射线光束垂直方向空间相干长度为8.84μm,对应的光源尺寸为23μm,测量结果与理论分析相符.

Coherence of X-ray in the third synchrotron radiation source

Since the third generation synchrotron radiation source came into service, the X-ray techniques which relate to coherent property have quickly developed and been widely used. Typically, X-ray phase contrast imaging has become a conventional imaging method. The X-ray techniques, such as coherence scattering, coherent diffraction imaging, and photon correlation spectroscopy, have received more attention and shown unique superiority in the field of high spatial and time resolution. So quantifying the coherent property of X-ray source is meaningful for those novel X-ray techniques. In this article, based on the Talbot self-imaging phenomenon, the spatial coherent property and the scale of X-ray source of X-ray imaging and biomedical application beam line in Shanghai synchrotron radiation facility are measured. The results show that when the photon energy is 33.2 keV, the spatial coherence length is 8.84 μm and source size is 23 μm in the vertical direction, and the test result is in agreement with the theoretical value.
Keywords： X-ray optics coherence length grating interferometer synchrotron radiation