  Dipoles interference is studied when atomic systems are coupled to classical
electromagnetic fields. The interaction between the dipoles and the classical
fields induces a time-varying Aharonov-Casher phase. Averaging over the phase
generates a suppression of fringe visibility in the interference pattern. We
show that, for suitable experimental conditions, the loss of contrast for
dipoles can be observable and almost as large as the corresponding one for
coherent electrons. We analyze different trajectories in order to show the
dependence of the decoherence factor with the velocity of the particles.
