| 摘要 |
PROBLEM TO BE SOLVED: To neutralize charges on a target. SOLUTION: A host computer determines a neutralizing beam current value based on the ratio of main beam current and neutralizing current corresponding to combination of the kind and the mode of a set target, and transmits an instruction signal corresponding to the determined neutralizing current value to a neutralizing gun control part 29, and also determines a neutralizing beam spot diameter based on a relation expression for determining spot diameter, and transmits an instruction signal corresponding to neutralizing beam spot diameter determined to the neutralizing gun control part 29. A neutralizing beam on, off instruction signal is transmitted to the neutralizing gun control part 29 from the host computer. The neutralizing gun control part 29 controls an electron gun 26 so that the current amount of electron beams becomes the determined current value, and controls lens strength of a focusing lens 24 so that the spot diameter on the target 6 of the electron beams becomes the determined size.
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