Geometrical phase analysis (GPA) is typically a powerful tool to investigate the deformation in high resolution transmission electron microscopy images and has been used in various fields. During GPA, strain components are calculated relative to an undistorted reference region. In the present work, the effect of reference region size on strain measurements has been investigated. Experimental measurements on a locally distorted gold nanoparticle exhibited that a small reference region below the GPA spatial resolution can introduce an inaccuracy in the measured displacement field, which appears as a significant increase in measured strains and severe fluctuation in phase images. The inaccuracy may be ascribed to an error of insufficient sampling. Our results suggest that a small reference region below the GPA spatial resolution should be avoided during GPA. This prerequisite should be paid more attention to during strain measurement on nanoparticles.

中文翻译：

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参考区域大小对使用几何相位分析的应变测量的影响

几何相位分析 (GPA) 通常是研究高分辨率透射电子显微镜图像变形的有力工具，已被用于各个领域。在 GPA 期间，相对于未失真的参考区域计算应变分量。在目前的工作中，已经研究了参考区域尺寸对应变测量的影响。对局部扭曲的金纳米粒子的实验测量表明，低于 GPA 空间分辨率的小参考区域会导致测量的位移场不准确，这表现为测量应变的显着增加和相位图像的严重波动。不准确可能归因于采样不足的错误。我们的结果表明，在 GPA 期间应避免低于 GPA 空间分辨率的小参考区域。在对纳米颗粒进行应变测量时，应更加注意这一前提条件。