| 摘要 |
PROBLEM TO BE SOLVED: To reduce readjustment caused by an erroneous operation and thereby to improve operability by varying the relation between the operation amount of one or more operation means and the actuation amount of an adjustment function due to it according to a cumulated value of the operation amount or a period from the operation start. SOLUTION: A system control means 14 connected to various kinds of operation knobs of an adjustment operation panel 50 controls an electron beam control part 13 of an electron beam 3 from an electron source 2, and secondary electrons are displayed on an image display 22 through a secondary electron detector 9, an image memory 18 and the like. A focus rough adjustment knob 51 is effective only in the case of low magnification, and a focus fine adjustment knob 52 and X, Y astigmatic correction knobs 53, 54 can effectively be used for adjustment in the case of high magnification. The adjustment amounts with the knobs are prevented from varying at the initial operation stage, so that the adjusted state is not deviated even if other knobs are mistakingly touched. After operation for a predetermined period, the system control means 14 controls the variation of the adjustment so as to set it to a normal value.
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