- Electron holography
Electron holography is the application of
holographytechniques to electron waves rather than light waves.
Point-like field emission sources are the appropriate sources for coherent electron waves. Unlike optical sources, the wavelength is not fixed but can be readily selected by means of the applied voltage.
The coherent beam needs to be split into at least two beams for interference. This can be done by grating diffraction or by use of an electron biprism (essentially a narrow wire filament).
It is important to shield the interferometric system from electromagnetic fields, as they can induce unwanted phase-shifts due to the
Aharonov-Bohm effect. Static fields will result in a fixed shift of the interference pattern. It is clear every component and sample must be properly grounded and shielded from outside noise.
Electron holography was invented by Dennis Gabor to improve the resolution and avoid the aberrations of the
transmission electron microscope. Today it is commonly used to study electric and magnetic fields in thin films, as magnetic and electric fields can shift the phase of the interfering wave passing through the sampleR. E. Dunin-Borkowski et al., Micros. Res. and Tech. vol. 64, pp. 390-402 (2004).] .
The principle of electron holography can also be applied to
interference lithographyK. Ogai et al., Jpn. J. Appl. Phys., vol. 32, pp.5988-5992 (1993) ] .
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