| 摘要 |
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.
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