  Surface charging is a phenomenon ubiquitously observable in in-situ
transmission electron microscopy of non-conducting specimens as a result of
electron beam/sample interactions or optical stimuli and often limits the
achievable image stability and spatial or spectral resolution. Here, we report
on the electron-optical imaging of surface charging on a nanostructured surface
following femtosecond-multiphoton photoemission. By quantitatively extracting
the light-induced electrostatic potential and studying the charging dynamics on
the relevant timescales, we gain insights into the details of the multi-photon
photoemission process in the presence of a background field. We study the
interaction of the charge distribution with the high-energy electron beam and
secondary electrons and propose a simple model to describe the interplay of
electron- and light-induced processes. In addition, we demonstrate how to
mitigate sample charging by simultaneous optical illumination of the sample.
