A common characteristic in semiconductor nanostructures is the lattice strain originating from the lattice mismatch between layers of different compositions. Three-dimensional strain measurement in crystals using transmission electron microscopy (TEM) techniques has been the subject of intense works for decades. This information is required for the strain-bandgap engineering being used by our current fast computers and necessary for future quantum computers. However, the missing information was the 3rd dimension that is the atomic displacement and how it changes along the electron-beam direction. The strain information along the electron-beam direction is in the phase of the diffracted beam, which has been obtained recently by the novel technique of self-interference of split higher order Laue zone line (SIS-HOLZ). SIS-HOLZ has been made possible by the correction of the beam aberrations having its analytical and experimental details reported here for the atomic displacement profile existing at the interface of a Si and Si/Si_0.8Ge_0.2 superlattice.