| 摘要 |
Spherical aberration correction optics are offered which have an auxiliary function of determining control parameters easily and at any time while canceling deflecting and quadrupole fields in the instrument. The correction optics have a control unit for determining the parameters of the aberration correction optics and parameters for canceling the deflecting and quadrupole fields, a power supply for applying electric potentials or magnetic potentials to the aberration correction optics based on a signal from the control unit, and a period-varying circuit positioned between the control unit and the power supply to add a signal whose amplitude is varied continuously at frequency f with respect to real time t.
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