Guidelines for quantitative reconstruction of complex exit waves in HRTEM

We have used a simple analytic model of iterative wave reconstruction from HRTEM focal series to derive reconstruction guidelines. We find that the reconstruction must be padded and that samples with varying thicknesses over the field of view can require a very large number of iterations to correctly converge. We also consider the effect of a detector modulation transfer function, noise and an incorrect estimate on focal plane spacing on iterative wave reconstruction. We have used multislice simulations in 1D and 2D and developed a high-speed, parallelized implementation of exit wave reconstruction to validate our analytic model and demonstrate why convergence is required for quantitative sample thickness measurements.