The tip forming procedure is monitored
by a MCP-detector that can be moved out of the optical
axis. The electrons start with an emission energy of
1.58 keV for the experiment with He and N2 background
gas and 1.44 keV for the one with H2. They coherently
illuminate a 400 nm wide gold covered biprism fiber that
divides and combines the electron matter waves [1,9]. It
is set on a positive potential of 0.35 V for the experiments
with He or N2 background gas and 0.4 V for H2. All beam
alignment is performed by electrostatic deflection
electrodes