Multipole lens and charged-particle beam instrument fitted with multiple lens

摘要

A multipole lens (4a) producing less magnetic field variations is offered. Also, a charged-particle beam instrument (1) fitted with such multipole lenses (4a) is offered. The multipole lens (4a) has plural polar elements (23), an annular holding member (25), and an annular yoke (29) disposed outside the holding member. Each polar element (23) has a held portion (22c) and a base-end portion (22b). The held portions (22c) of the polar elements (23) are held by the holding member (25). The yoke (29) is magnetically coupled to the base-end portions (22b) of the polar elements (23). The yoke (29) is provided with openings (29a) extending circumferentially. The base-end portions (22b) of the polar elements (23) are positioned in the openings (29a).