The recently described tests of the synchrotron imaging photoelectron spectromicroscope MEPHISTO (Microscope a Emission de PHotoelectrons par Illumination Synchrotronique de Type Onduleur) were complemented by further resolution improvements and tests, which brought the lateral resolution down to 20 nm. Images and line plot profiles demonstrate such performance. (C) 1999 American Institute of Physics. [S0034-6748(99)04902-3].