Ram Farangis, Wright Stuart, Singh Saransh, De Graef Marc
Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
EDAX, 392 East 12300 South, Suite H, Draper, UT 84020, USA.
Ultramicroscopy. 2017 Oct;181:17-26. doi: 10.1016/j.ultramic.2017.04.016. Epub 2017 Apr 29.
The efficacy of the dictionary approach to Electron Back-Scatter Diffraction (EBSD) indexing was evaluated through the analysis of the error in the retrieved crystal orientations. EBSPs simulated by the Callahan-De Graef forward model were used for this purpose. Patterns were noised, distorted, and binned prior to dictionary indexing. Patterns with a high level of noise, with optical distortions, and with a 25 × 25 pixel size, when the error in projection center was 0.7% of the pattern width and the error in specimen tilt was 0.8°, were indexed with a 0.8° mean error in orientation. The same patterns, but 60 × 60 pixel in size, were indexed by the standard 2D Hough transform based approach with almost the same orientation accuracy. Optimal detection parameters in the Hough space were obtained by minimizing the orientation error. It was shown that if the error in detector geometry can be reduced to 0.1% in projection center and 0.1° in specimen tilt, the dictionary approach can retrieve a crystal orientation with a 0.2° accuracy.
通过分析所检索晶体取向的误差，对字典法进行电子背散射衍射（EBSD）索引的有效性进行了评估。为此使用了由卡拉汉 - 德格雷夫正向模型模拟的电子背散射花样（EBSP）。在进行字典索引之前，对花样进行了噪声添加、畸变处理和像素合并。当投影中心误差为花样宽度的0.7%且试样倾斜误差为0.8°时，对于具有高噪声水平、光学畸变且像素尺寸为25×25的花样，其取向索引的平均误差为0.8°。相同的花样，但像素尺寸为60×60，通过基于标准二维霍夫变换的方法进行索引时，取向精度几乎相同。通过最小化取向误差获得了霍夫空间中的最佳检测参数。结果表明，如果探测器几何误差在投影中心可降低到0.1%，在试样倾斜方面可降低到0.1°，则字典法能够以0.2°的精度检索晶体取向。
