Interferometry using convergent electron diffracted beams plus an electron biprism (CBED + EBI)

A method of interferometry which interferes convergent electron beams by means of an electron biprism, CBED + EBI, is presented. The method requires an electron biprism which is placed below the specimen and in between any two or more convergent beams. The biprism compensates the convergent beams deviation angle by means of an applied potential. When overlaid the diffracted beams interfere to produce an interferogram. Theoretical and practical descriptions of the CBED + EBI method are presented, as well as some of its special features such as its ability to interfere high spatial frequency beams, to produce high contrast fringes and to measure the electron beamʹs coherency.