A Michelson interferometer using electron waves

Abstract

An electron interferometer of the Michelson type is realized. Monoenergetic 25 keV electrons emitted from a line source 1000 Å in width are deflected by 90 ° in a magnetic Castaing prism and reflected on two mirrorsM ₁ andM ₂ held at a potential ΔU _m negative with respect to the cathode. In the experiment the mirrors are represented by height differences on the surface of an silvered glass plate. The reflected electrons are once more deflected by the magnetic prism behind which the coherent partial beams 1 and 2 reflected on the mirrorsM ₁ andM ₂, respectively, are superimposed using an electrostatic biprism to form two-beam interferences. The observed fringe shift indicates a phase shift due to differences in height between the equipotentials reflecting the partial beams 1 and 2. It is estimated that path differences less than the electron wavelength of 0.08 Å can be observed.