Observation of Magnetic Fine Structures by Electron Differential Microscopy

New techniques for electron differential interferometry and microscopy that are free from the effect of distorted reference waves have been developed using an electron trapezoidal prism. This new prism, which replaces an electron biprism, makes a hologram with the object wave inclined and the reference wave perpendicular to the image plane. A differential interferogram can be produced from one double-exposed hologram. A differential phase image from two independently recorded holograms can also be easily achieved. These two techniques retain the advantages of conventional off-axis electron holography, that is, resolution and sensitivity. Their performance is evaluated by reconstructing the electrostatic potential around a charged polystyrene latex particle and by the observation of magnetic fine structures in a permalloy thin film. A two-dimensional vector map of the magnetic flux density enables an interpretation of the contrast of the Lorenz micrograph of the same specimen area.