Nishi R, Moriyama Y, Yoshida K, Kajimura N, Mogaki H, Ozawa M, Isakozawa S
Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
Microscopy (Oxf). 2013;62(5):515-9. doi: 10.1093/jmicro/dft030. Epub 2013 May 12.
An accurate method using image sharpness to determine the best focusing is proposed for ultra-high-voltage electron microscopy. This method maximizes image sharpness for adjusting the focus. Five images with different defocus values are used to calculate the image sharpness. To obtain the best focus value that produces greatest image sharpness, fitting the quasi-Gaussian function to five image sharpness is a suitable alternative. This method, which maximizes image sharpness, gives better accuracy than the wobbler method for the ultra-high-voltage electron microscope. The focusing area can be selected without moving the field of view, because the focusing area can be selected at almost any area in the image.
提出了一种利用图像清晰度来确定最佳聚焦的精确方法，用于超高压电子显微镜。该方法通过调整聚焦使图像清晰度最大化。使用具有不同散焦值的五幅图像来计算图像清晰度。为了获得产生最大图像清晰度的最佳聚焦值，将准高斯函数拟合到五个图像清晰度上是一种合适的选择。这种使图像清晰度最大化的方法，对于超高压电子显微镜而言，比摆动法具有更高的精度。由于可以在图像中的几乎任何区域选择聚焦区域，因此无需移动视场即可选择聚焦区域。
