An Anomalous Contrast of Insulators in Scanning Electron Microscope: The   Split Image
  A novel phenomenon of anomalous contrast in scanning electron microscope when the instrument is used to observe an insulator specimen with a wolfram probe, we called double imaging, is reported in this article. We give a detail analysis of this phenomenon in its occurrence, and discuss the influence of the added probe to internal electric field which lead to the occurrence of double imaging. 
Lilin Xie, Xiaona Zhang
cond-mat.mtrl-sci