Optical system for double-biprism electron holography

A novel system of electron interferometry and holography using two electron biprisms has been developed. The first biprism is installed in the image plane of the objective lens and the second one is set behind the first magnifying lens, inside the shadow area of the first biprism. The system can independently control two important parameters for interferograms and holograms, the fringe spacing and interference width. Thus, it gives us more flexibility on performing electron interferometry and holography. The good performance of the system was demonstrated using a 1 MV field-emission electron microscope. We introduce a variety of optical set-ups for the system and explain the advantages of each set-up in detail, with experimental results.