An apparatus adapted for the analysis of a surface of a sample (1) comprises: means (7) for stimulating a region of said surface to emit charged particles; means for moving a light reflecting means (16) in a substantially rectilinear fashion along an optical axis of a microscope (28) to a position where it reflects an image of said region to said microscope (28); and means for moving an extraction electrode (15) in a substantially rectilinear fashion in a direction substantially parallel to, or coincident with, said optical axis to a position where said charged particles pass through an aperture in said extraction electrode (15) to a charged particle analyser (10). The invention allows both the direction of extraction of charged particles and the direction along which said surface is viewed, to be coincident and perpendicular to said surface.