While electron holography has been around for many years (1948, see [1]), the process of obtaining a view into the phase world stayed a tedious one for a long time. When CCD cameras became available and started to replace film, many attempts were made to obtain a “live” view into the phase world. By far the most successful setup for a live phase display is described in [2]. There, Chen et al. use a mixture of digital and analog techniques to obtain phase images at TV-rate. This setup allows to move the sample and/or watch time dependent specimen changes in a unique way, i.e., live in the phase world. The reason why Chen uses a mixture between analog and digital methods is the capability of an optical lens system for fast Fourier processing.

Computers have become significantly faster since Chen's introduction of the mixed setup in 1992 and allow to process holograms rapidly and obtain about one phase image per second on present standard computer systems and acquisition cameras.