The invention relates to an energy filter image generator for filtering electrically charged particles. The inventive energy filter comprises at least two toroidal energy analysers (30, 40) arranged one inside the other. A transfer lens device (20) is disposed between the plane of emergence (5) of the first energy analyser (30) and the plane of incidence of the second energy analyser (40), thereby making it possible to obtain the perfect energy filtered reproduction of the surface (1') of a sample on a detector (10).