Signal separator for a multi-beam charged particle inspection apparatus

A multi-beam charged particle column for inspecting a surface of a sample includes a source for creating multiple primary charged particle beams which are directed towards the sample, an objective lens unit for focusing the primary charged particle beams on the sample, a detector for detecting signal charged particles from the sample, and a magnetic deflection unit arranged between the detector and the sample. The magnetic deflection unit includes a plurality of strips of a magnetic or ferromagnetic material. At least two strips of the plurality of strips are located at opposite sides of a trajectory of a primary charged particle beam and within a distance equal to a pitch of the trajectories of the primary charged particle beams at the magnetic deflection unit. The strips are configured to establish a magnetic field having field lines substantially perpendicular to the trajectories of the primary charged particle beams.