| 摘要 |
PURPOSE:To improve the voltage measuring accuracy, by furnishing independent coils to respond to at least two gaps at an object lens, and controlling the current ratio to the coils responding to the variation of the energy analysis voltage. CONSTITUTION:At the inside of an object lens device 1 with two gaps 4 and 5, and two coils 2 and 3 independent each other and opposing to the gaps 4 and 5, energy analysis devices 9 to 14 for detecting secondary electrons are arranged, to composed an electron beam device. In this case, the ratio of the exciting currents of the coils 2 and 3 is controlled responding to the variation of the analysis voltage VR fed to the analysis devices 9 to 14. While the focusing condition of the primary electron beams 19 is being kept almost constant, the focusing property of the secondary electrons 20 analyzed by the analysis devices 9 to 14 is made almost constant. Therefore, the capturing property of the secondary electrons 20 is always maintained constant, and the voltage measuring accuracy and the the expansion of the dynamic range can be realized.
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