  Previously reported crystalline structures obtained by an iterative phase
retrieval reconstruction of their diffraction patterns seem to be free from
displaying any irregularities or defects in the lattice, which appears to be
unrealistic. We demonstrate here that the structure of a nanocrystal including
its atomic defects can unambiguously be recovered from its diffraction pattern
alone by applying a direct phase retrieval procedure not relying on prior
information of the object shape. Individual point defects in the atomic lattice
are clearly apparent. Conventional phase retrieval routines assume isotropic
scattering. We show that when dealing with electrons, the quantitatively
correct transmission function of the sample cannot be retrieved due to
anisotropic, strong forward scattering specific to electrons. We summarize the
conditions for this phase retrieval method and show that the diffraction
pattern can be extrapolated beyond the original record to even reveal formerly
not visible Bragg peaks. Such extrapolated wave field pattern leads to enhanced
spatial resolution in the reconstruction.
