| 摘要 |
PURPOSE:To prevent deflecting field intensity from weakening due to the effect of eddy current generated in a liner tube by differentiating an output of deflecting current and superposing said output on the deflecting current which is supplied to a deflecting coil. CONSTITUTION:A deflecting device for a scanning electron microscope or the like is formed by placing a deflecting coil 3 outside the liner tube 2 made of stainless steel which is provided along the optical axis 1 of electron rays and the output of a circuit 4 for generating a scanning signal is supplied to the deflecting coil 3 through a circuit 5 for controlling amplitude and a summing circuit 6. At this time, the device is formed to add the differential circuit 7 to an output of the circuit 5 for controlling the amplitude and to input its output to one side of the summing circuit 6. Thus, a component of differential signal undertakes a component of deflecting current which contributes to the generation of an eddy current in the liner tube 2 by superposing the component of differential signal on the scanning current and therefore it is possible to generate a deflecting field with original intensity within the tube 2.
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