the present invention relates to an orbit correction method for a charged particle beam , and aims to solve problems inherent in conventional aberration correction systems and to provide a low - cost , high - precision , high - resolution optical converging system for a charged particle beam . to this end , employed is a configuration in which a beam orbit is limited in ring zone form to form a distribution of electromagnetic field converging toward the center of a beam orbit axis . consequently , a nonlinear action outwardly augmented , typified by spherical aberration of an electron lens , can be cancelled out . specifically , this effect can be achieved by an electron disposed on the axis and subjected to a voltage to facilitate the occurrence of electrostatic focusing . for a magnetic field , this effect can be achieved by forming a coil radially distributed - wound on a surface equiangularly divided in the direction of rotation to control convergence of a magnetic flux density .