| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an electron beam device provided with a field emission type electron gun which can perform an accurate automatic flashing by automatically determining abnormalities of operations of an FEG. SOLUTION: The field emission type electron gun provided with a field emission emitter, an extraction electrode having the emitter emit electrons, an accelerating electrode for accelerating the electrons emitted by the emitter, an extraction power source controlling the extraction voltage applied on the extraction electrode, and an emission current detection means detecting a part of the electrons emitted from the emitter, is further provided with a means for detecting decrease of emission current exceeding a certain threshold limit, a means for variably controlling extraction voltage to have the emission current return to the certain current based on the output of the detection means, a means for determining a state of the field emission emitter based on the change of the extraction voltage, and a means for automatically flashing according to the decision.</p> |
