| 摘要 |
An aberration corrector comprises four stages of electrostatic quadrupole elements, two stages of electrostatic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central ones of the four stages of the electrostatic quadrupole elements on the electric potential distribution, an objective lens, a manual operation portion permitting a user to modify the accelerating voltage or the working distance, a power supply for supplying voltages to the four stages of electrostatic quadrupole elements, a power supply for exciting the two stages of magnetic quadrupole elements, a power supply for the objective lens, and a control portion for controlling the power supplies according to a manual operation or setting performed on the manual operation portion.
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