A study of electric charging using low-magnification electron holography

As experimentally found by low-magnification holography, both the size of t he condenser aperture and the excitation of the objective lens strongly mod ify the object wavefunction of an electron wave. For example, the phase by electrically charged polystyrene latex spheres attached to a copper grid in creases with decreasing excitation of the objective lens and/or decreasing diameter of the condenser aperture. It was also found that a smaller diamet er of the condenser aperture increases the phase shift by a carbon foil or magnetic memory cells. In addition, the phase of the image wave is modified by the lateral position of the aperture, whereas different electron densit ies of the imaging beam have only minor influence on the detected phase shi fts. (C) Elsevier Science Inc., 1999. All rights reserved.