In this paper, we report that the far field diffraction pattern of a specimen which is consisting of an array of spherical particles enables the determination of the size and refractive index of each scattering sphere. The far field 2D angular resolved diffraction pattern, of which the diffraction angle reaches tens of degrees, is measured by CCD camera. On one hand, the diffraction pattern distorted obviously at high angles is corrected for curvature. The amplitude and phase images of the specimen are reconstructed by difference map iterative algorithm. The size of each scattering microsphere is calculated according to its pixel numbers and the image resolution. On the other hand, the diffraction pattern without curvature correction is used to reconstruct the amplitude and phase images of the specimen by HIO algorithm. The amplitude and phase images of each sphere are isolated. Then the angular resolved scattering signals of the individual spheres are quantitatively indicated by Fourier transform. Finally, the refractive index of each microsphere is obtained by fitting the experimental results using Mie theory.

中文翻译：

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通过傅里叶变换对多个球形粒子进行角度分辨散射测量

在本文中，我们报告了由一系列球形粒子组成的样本的远场衍射图案，可以确定每个散射球的大小和折射率。远场二维角分辨衍射图，其衍射角达到几十度，由CCD相机测量。一方面，在高角度明显扭曲的衍射图案被校正曲率。通过差分图迭代算法重建样本的幅度和相位图像。每个散射微球的大小根据其像素数和图像分辨率计算。另一方面，没有曲率校正的衍射图案用于通过 HIO 算法重建样品的幅度和相位图像。每个球体的幅度和相位图像是隔离的。然后通过傅立叶变换定量表示各个球体的角分辨散射信号。最后，利用米氏理论对实验结果进行拟合，得到每个微球的折射率。