On correction of translational misalignments between section planes in 3D EBSD.

ABSTRACT

Three-dimensional electron backscatter diffraction allows obtaining the 3D image of a material from the stack of 2D sections. This is achieved by repeated application of two different beams; electron beam for electron backscatter diffraction mapping of the surface and focused ion beam for removing a thin layer of material from the surface. In most of these systems with two beams, the experiment requires stage movements for correct positioning of the sample to the respective beams. However, imperfections in this positioning are difficult to avoid, which yield small translational misalignments between the sections in the output data. In this work, we deal with an important task of correcting these misalignments between the sections such that the 3D image is recovered properly. On a simple example, we demonstrate that commonly used methods fail in case there is a structural anisotropy in the material under consideration. We propose an improved alignment algorithm which can neglect this behaviour with the use of external support information on a systematic trend in the translational misalignments. Efficiency of the algorithm is proven on a number of simulated data with different kinds of anisotropy. Application to a real data sample of a fine grained aluminium alloy is also given. The algorithm is available in an open-source library.