| 摘要 |
PURPOSE:To obtain a sample image with magnification in accordance with indicated magnification by installing an auxiliary lens and supplying an auxiliary lens with an excited current necessary for correcting a difference between the indicated observation magnification and actual observation magnification. CONSTITUTION:While an input device 18 is operated by an operator so that an acceleration voltage U9 is indicated, observation magnification M is indicated. A CPU 16 reads a signal from the device 18, and it makes an output voltage of an acceleration power source 2 correspond to the voltage U9, and it reads excitation indicating data corresponding to the voltage U9 from a memory device 17 and sends the data to an auxiliary lens power source 13. On the other hand, a CPU 16 sends the excitation current indicating signal in accordance with the magnification M to an intermediate lens power source 14 and a projection lens power source 15. Subsequently, an image based on electron beams passing through a sample 5 is focused as an image Im1 by the functions of an object lens 6 and the auxiliary lens 7, on a position nearer to an object lens 6 side than the position in the case where the lens 6 is used individually. subsequently, a final image Im3 is focused on a fluorescent plate 10, and so this image of magnification M can be observed from the fluorescent screen 10.
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