Reconstruction of electron off-axis holograms: a new and fast alternative method

Abstract

In a conventional electron microscope the image intensity, i.e. the sum of the modulus square of the elastic image wavefunction and the intensity of the inelastically scattered electrons is recorded. The information of the phase of the elastic image wavefunction is lost. From an image-plane off-axis hologram, however, the image phase and image amplitude, i.e. the phase and the modulus (“amplitude”) of the elastic image wavefunction, may be reconstructed using fast Fourier algorithms. However, the conventional reconstruction of holograms requires a large amount of processing time. A new alternative reconstruction procedure is presented which avoids the fast Fourier algorithm. It allows an extremely fast and convenient determination of the image phase and image intensity. The display of image phase and intensity at TV rate appears to be possible, but is limited so far by the read-out time of the CCD camera.