Geometric phase analysis

Geometric phase analysis is a method of digital signal processing used to determine crystallographic quantities such as d-spacing or strain from high-resolution transmission electron microscope images.

In geometric phase analysis, local changes in the periodicity of a high resolution image of a crystalline material are quantified, resulting in a two-dimensional map.

Quantities which can be mapped with geometric phase analysis include interplanar distances (d-spacing), two-dimensional deformation and strain tensors and displacement vectors.

Together with a vector of one crystallographic plane depicted in the image, the amplitude and phase can be used to generate a 2D map of d-spacing.

Secondly, a vector of crystallographic plane is an important input parameter and the analysis is sensitive to the accuracy of its localization.

Geometric phase analysis performed by CrysTBox gpaGUI showing input image (bottom left) and d-spacing map (bottom right)