Aberration Corrector and Charged-Particle Beam System Equipped Therewith

An aberration corrector for a charged-particle beam, comprising:

• two stages of dodecapole elements, each of the dodecapole elements having first through twelfth poles arranged in this order;
• and
• exciting coils mounted at the poles, respectively, of each of the dodecapole elements,
• wherein the exciting coils of the (4n+1)th poles and the exciting coils of the (4n+2)th poles are alternately connected in series (where n=0, 1, or 2) and produce magnetic fields which are identical in absolute value but mutually opposite in sense relative to an optical axis within a plane perpendicular to the optical axis, and
• wherein the exciting coils of the (4n+3)th poles and the exciting coils of the (4n+4)th poles are alternately connected in series and produce magnetic fields which are identical in absolute value but mutually opposite in sense relative to the optical axis within the plane perpendicular to the optical axis, whereby a superimposition of the magnetic fields of 3-fold symmetry and the magnetic fields of 6-fold symmetry is produced.