Tsai Yi-Yun, Pan Yi-Chen, Kuo Jui-Chao
Department of Materials Science and Engineering, National Cheng-Kung University, Tainan, 701, Taiwan.
Sci Rep. 2022 Jan 10;12(1):399. doi: 10.1038/s41598-021-04407-0.
A raw electron backscatter diffraction (EBSD) signal can be empirically decomposed into a Kikuchi diffraction pattern and a smooth background. For pattern indexing, the latter is generally undesirable but can reveal topographical, compositional, or diffraction contrast. In this study, we proposed a new background correction method using polynomial fitting (PF) algorithm to obtain clear Kikuchi diffraction patterns for some applications in nonconductive materials due to coating problems, at low accelerated voltage and at rough sample surfaces and for the requirement of high pattern quality in HR-EBSD. To evaluate the quality metrics of the Kikuchi patterns, we initially used three indices, namely, pattern quality, Tenengrad variance, and spatial-spectral entropy-based quality to detect the clarity, contrast, and noise of Kikuchi patterns obtained at 5 and 15 kV. Then, we examined the performance of PF method by comparing it with pattern averaging and Fourier transform-based methods. Finally, this PF background correction is demonstrated to extract the background images from the blurred diffraction patterns of EBSD measurements at low kV accelerating voltage and with coating layer, and to provide clear Kikuchi patterns successfully.
原始电子背散射衍射（EBSD）信号可以通过经验分解为菊池衍射花样和平滑背景。对于花样索引，后者通常是不需要的，但可以揭示形貌、成分或衍射对比度。在本研究中，我们提出了一种使用多项式拟合（PF）算法的新背景校正方法，以在一些应用中获得清晰的菊池衍射花样，这些应用包括由于涂层问题、低加速电压和粗糙样品表面而导致的非导电材料应用，以及高分辨电子背散射衍射（HR-EBSD）对高花样质量的要求。为了评估菊池花样的质量指标，我们最初使用了三个指标，即花样质量、 tenengrad方差和基于空间谱熵的质量，来检测在5 kV和15 kV下获得的菊池花样的清晰度、对比度和噪声。然后，我们通过将PF方法与花样平均法和基于傅里叶变换的方法进行比较，来检验PF方法的性能。最后，证明了这种PF背景校正能够从低kV加速电压和有涂层的EBSD测量的模糊衍射花样中提取背景图像，并成功地提供清晰的菊池花样。
