| 摘要 |
PROBLEM TO BE SOLVED: To suppress contamination of a sample by electron ray irradiation within a tolerance level. SOLUTION: Voltage is impressed to a deflecting electrode 6, all the electron rays irradiated to the sample are irradiated to a Faraday cup 5, and an irradiated current to the sample 4 is measured by a current detector circuit 7. Then, by a CPU1, the amount of dose is calculated with an operation from the irradiation current, a set magnification, and an irradiation time (irradiation current per unit area×irradiation time). An actual amount of dose and an actual electron ray irradiation time accompanying with the amount of dose permitted to the sample, and the irradiation time, are managed by showing in an image display device. When the amount of dose reaches an acceptable limit, voltage is impressed to the deflecting electrode 6 and the electron ray irradiation to the sample 4 is stopped.
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