| 摘要 |
PROBLEM TO BE SOLVED: To observe and record the state change of the whole of a sample under the optimum lens condition even with respect to a case having to set spatially or time-like different lens conditions. SOLUTION: A sample observation part 50 has an electronic lens system consisting of a cathode lens 1, an intermediate lines 2 and a projection lens 3 in order to observe the sample 9 in a vacuum chamber 6. A setting condition like the correction of the focus and astigmatism of the electronic lens system is modulated with the elapse of time by a focus control part 51. The image signal of the sample 9 photographed by a video camera 10 is branched on the basis of each setting condition by a signal branching circuit 18, and an image at every setting condition is displayed on first and second monitors 19, 20.
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