SMS Centre, UMR CNRS 5146, Ecole des Mines de Saint-Etienne, 158 cours Fauriel, 42023 Saint-Etienne, Cedex 2, France.
Ultramicroscopy. 2011 Jan;111(2):140-8. doi: 10.1016/j.ultramic.2010.10.007. Epub 2010 Oct 20.
The moving screen technique for pattern centre localisation is revisited. A cross-correlation based iterative procedure is developed to find both the zoom factor and the zoom centre (which is also the pattern centre) between two EBSD diffraction patterns acquired at two camera positions. The procedure involves two steps: first, a rough estimate of the pattern centre position and zoom factor (the ratio of the two detector distances) is obtained by cross-correlating the entire images. Then, based on this first estimate, cross-correlation of smaller regions of interest (ROIs) gives the displacement field which is interpreted as a zoom factor misfit coupled with a zoom centre position misfit. These misfits are iteratively decreased until the displacement field is reduced to the noise level. The procedure is first applied to simulated patterns and it is shown that the iterative procedure converges very rapidly to the exact solution with an accuracy better than 1/100th of pixel. The potential of this technique for experimental patterns is discussed and recommendations for new EBSD detectors are proposed.
本文重新探讨了花样中心定位的动镜技术。开发了一种基于互相关的迭代程序，用于在两个相机位置获取的两个 EBSD 衍射花样之间找到缩放因子和缩放中心（也是花样中心）。该程序包括两个步骤：首先，通过对整个图像进行互相关，可以粗略估计花样中心位置和缩放因子（两个探测器距离的比值）。然后，基于这个初步估计，对较小的感兴趣区域（ROI）进行互相关，可以得到位移场，该位移场被解释为缩放因子不匹配以及缩放中心位置不匹配。通过迭代减小这些不匹配，直到位移场减小到噪声水平。该程序首先应用于模拟花样，结果表明，迭代程序能够非常快速地收敛到精确解，精度优于 1/100 像素。讨论了该技术在实验花样中的潜力，并提出了对新型 EBSD 探测器的建议。
