Figure 1

Fringes observed in a single-electron-buildup experiment in which the electron dose is controlled by the exposure time: (a) approximately 50 electrons were counted in the panel in 0.1 s in the viewing area, (b) approximately 500 electrons in 1.0 s, (c) approximately 5,000 electrons in 10 s, and (d) approximately 50,000 electrons in 100 s.