Fig. 3.

The build-up of charge during imaging. Representative images of Berriman build-up. Each panel shows a different region of the holey carbon with amorphous ice from different widely-separated grid squares immediately after irradiation with a  5 µm diameter primary beam using increasing electron doses. The image in each panel was recorded under the same conditions as used for Fig. 2b, with increasing doses of 4.7$\times {10}^{-4},$ 1.4$\times {10}^{-3},$ 1.4$\times {10}^{-2},$ 1.4$\times {10}^{-1},$ 1.4 and 14 e${}^{-}$/Ų in the central region. The results of this series are analysed quantitatively in Fig. 4(c). Scale bar is 5 µm.