REFLECTION ELECTRON HOLOGRAPHY

Off-axis reflection electron holograms of single-crystal surfaces have been recorded by superposing two wave fields reflected from different areas under resonance condition using a Mollenstedt biprism above the image plane. By EELS recording it was established that the fringe mod ulation is mainly due to elastically scattered electrons while the ine lastic background reduces the fringe contrast. Measured phase shifts a t atomic steps agree well with estimates deduced from a simple geometr ical model. Numerical reconstruction of the holograms allows the separ ation of the amplitude and phase contributions with elimination of bot h the inelastic background and the defocus. The measured transition wi dth above 10 nm of the phase at the steps as well as the remaining in- focus amplitude may indicate an influence of the strain field.