Phase sensitive analysis of electron holograms

Holography has been used in electron microscopy since the field emission electron microscope was developed.[1] Tonomura et al described the interference microscope based on the electron holography to evaluate microscopic distribution of the magnetic field. [2] To gain high sensitivity the use of the optical phase multiplication technique was discussed so as to obtain 10 time magnification of the reconstructed phase. [3] Recently Takeda et al applied the FFT method of the subfringe analysis for electron holographic fringes.[4] They mentioned phase variations much smaller than 2 π could be detected without recource to optical reconstruction or optical interferometric measurements.