A method and system are presented for directing a charged particle beam towards and away from a sample. The system comprises a lens arrangement having an electrode formed with a beam opening for a charged particle beam passage therethrough; and a magnetic deflector. The magnetic deflector has a magnetic circuit formed by a core part for carrying excitation coils and a polepieces part. The polepieces of the magnetic deflector are in electrical communication with the electrode of the lens arrangement and are electrically insulated from the other part of the magnetic circuit.