Magnetic electron lens

摘要

In a scanning electron microscope, an objective lens field is generated between a pair of deflecting coils and a specimen by an objective lens having upper and lower magnetic pole pieces. A supplemental magnetic pole piece is installed between said upper and lower magnetic pole pieces so that the half width of the objective lens axial magnetic field distribution is increased and the principal plane of the objective lens is positioned near the lower pole piece. By so doing, the spherical aberration coefficient of the objective lens is reduced and a high resolution scanning image is obtained.