| 摘要 |
When an accelerating voltage and operating distance are changed, an excitation current and a pole voltage of an aberration corrector must also be changed. Moreover, different multipole voltages or currents must be added individually for each pole in order to superpose multipoles. In view of overcoming the problems explained above, the charged particle optical apparatus of the present invention comprises an excitation device including, to give excitation to form a multipole field to each pole of the multipole lens, electromagnetic type quadrupole of four stages arranged along an optical axis of charged particle beam, electromagnetic type quadrupole of two stages for superposing distribution of voltage similar to distribution of magnetic potential of the electromagnetic type quadrupole of two stages at the center of the electromagnetic type quadrupole of four stages, and electromagnetic type octupole for superposing magnetic potential at least to three multipoles among that of four stages and also comprises a first power supply group for driving the same excitation device and a second power supply group for impressing voltages.
|
