Interferometry experiment carried out with a charged filament using the celadonite source. Electron energy: E_e = 227 eV, projection distance D = 86 cm, inter-source distance: a = 280 ± 30 nm, source-object distance d = 15 ± 3 μm, fringe-to-fringe distance i = 0.24 mm. Contrast Γ depends on source size, here estimated at s < 1.5 nm. The biprism is a charged ϕ = 118 nm diameter filament of an electrical grounded lacey carbon film.