Tomographic reconstruction sets atom probe tomography apart from most other atomic-resolution microscopy techniques and in some ways makes it more powerful. APT offers an unprecedented ability to map the positions of individual atoms in three dimensions to reveal the structural arrangement of the atoms inside a material is unprecedented. This chapter begins with an introduction of the main principles of the ion projection. We then present the procedure used to build the tomographic reconstruction of the analysed volume atom-by-atom, including descriptions of its performance along with its intrinsic limitations and some typical artefacts in the reconstructed data. Methods to address these limitations are discussed. Further, an approach for measuring the spatial resolution of the reconstruction is presented, along with discussion of the experimental and analytical factors affecting these values. This chapter closes with a description of lattice rectification, an extension to the conventional reconstruction algorithm providing a lattice-based reconstruction.
