Coïsson R
Appl Opt. 1995 Feb 10;34(5):904-8. doi: 10.1364/AO.34.000904.
The spatial coherence properties of a monochromatic component of synchrotron radiation from an insertion device in the Fraunhofer limit are analyzed in the general case when the coherence distance is comparable with the beam width, expressing them by simple products and convolutions of Fourier transforms and autocorrelations on the single-electron field amplitude and the electron-beam position and angular distributions. In particular, the Gaussian approximation is discussed, in which case the far-field amplitude satisfies the Schell condition (its statistical properties can be described by a coherence factor depending only on the difference of the reciprocal space coordinates), and this discussion leads to simple estimates of the coherence widths. The coherence widths deviate from the Van Cittert-Zernike values when one or more of the phase space widths of the electron beam are close to (or smaller than) the diffraction limit.
在相干距离与束宽相当的一般情况下，分析了来自插入式器件的同步辐射单色分量在夫琅禾费极限下的空间相干特性，通过单电子场振幅以及电子束位置和角分布的傅里叶变换与自相关的简单乘积和卷积来表示这些特性。特别讨论了高斯近似，在这种情况下，远场振幅满足谢尔条件（其统计特性可用仅依赖于倒易空间坐标差的相干因子来描述），并且该讨论得出了相干宽度的简单估计。当电子束的一个或多个相空间宽度接近（或小于）衍射极限时，相干宽度会偏离范西特 - 泽尼克值。
