ON THE ITERATIVE RESTORATION OF THE EXIT PLANE-WAVE FUNCTION FROM DEFOCUS SERIES IN HREM

The accuracy and the convergence rate of the maximum likelihood method of the electron wave function restoration from defocus series has been analyzed assuming that the imaging conditions are known. The procedure is found unstable near the exact solution if some other parameters are refined along with the wave function. The effects of the random noise in defocus series and of the dynamical scattering are discussed. The noise control offered by the MIMAP approach is found not effective under the common imaging conditions used in HREM. The wave function can be restored with reasonable accuracy from the noisy defocus series with the spatial resolution equal to the "information" limit of the electron microscope.