Digital extraction of the magnetic-flux distribution from an electron interferogram

Abstract

A phase-fitting method is proposed for correctly extracting the magnetic-flux distribution from a low-quality electron interferogram. The method is based on the use of the property ∇ × B = 0, which static magneticflux density B in vacuum must satisfy. It is derived from the property that the electron-wave phase distribution caused by magnetic fields satisfies the harmonic condition ∇2ϕ(x, y) = 0 but most of phase errors do not. A series of harmonic polynomial expressions is given and is used to fit the noisy phase data. The performance of the proposed method is shown by practical experiments.