[en] The performance of the electron beam interformeter are discussed. When the interferometer is based on the observation of an interference pattern the original incident beam has to be well-collimated and the allowable misalignment is small. This allowable misalignment increasing with the angle spread of the incident electron beams a convergent electron beam can be used. The electron interferometer based on amplitude interferences is more advantageous. The amplitude interference may be accomplished through the Fraunhofer diffraction of two coherent beams by a crystal, a convergent electron beam is also used