Wave function reconstruction in HRTEM: the parabola method

The non-linear parabola method for wave function reconstruction in HRTEM is presented in detail. It consists of an iterative procedure in which the linear and non-linear contributions to HRTEM images of a defocus series are optimally separated which will allow to benefit from a fast linear reconstruction scheme in which the non-linear contribution is corrected for in a self-consistent way. The method has proven to be a fast and workable algorithm for quantitative wave function reconstruction with direct resolution improvement. Results are shown for wave function reconstruction on experimentally acquired defocus series for a 200 keV FEG-TEM with a point-to-point resolution of 0.24 nm. In the reconstructed wave functions the resolution could clearly be enhanced up to 0.14 nm.