Incoherent electron holography

Abstract

Amplitude-division electron holography achieved in a nonbiprism transmission electron microscope is presented. A single-crystal thin film is used to divide the amplitude of the incident electron beam. The lattice fringes of the crystal film are used to form off-axis holograms. The relation between the spatial coherence of the illuminating beam and the resolution of the reconstructed image is derived and compared with that of the conventional wave-front-division holography achieved with a biprism. It is shown that using a low-coherence illuminating beam will reduce the resolution of the reconstructed images in the amplitude-division holography, whereas it will reduce sensitivity in conventional wave-front-division holography. Experimental results obtained using a gold crystal thin film as the beam splitter show that the amplitude-division electron holography permits any coherent or incoherent illumination when high resolution is not strongly required. Advantages over the wave-front-division electron holography achieved with a biprism system have been pointed out.