THE PHASE-SHIFT METHOD IN ELECTRON-OFF-AXIS HOLOGRAPHY - USING NEURAL-NETWORK TECHNIQUES

The common technique to extract amplitude and phase of the complex ele ctron image wave from off-axis electron holograms is based on a band-p ass filter that is applied to the spectrum of the hologram; therefore the carrier frequency of the hologram fringes has to be sufficiently h igh. The phase-shift method, which is well known from light-optical in terferometry, uses three holograms each with a specific shift in the l ateral position of the fringes to reconstruct amplitude and phase in r eal space, thus avoiding the need for fine hologram fringes. Neural ne tworks are used for the reconstruction of the image wave and compared in performance with the analytical method.