| 摘要 |
PURPOSE:To obtain a small-sized device which has good transportation efficiency and can effectively utilize the opening for a beam having an elliptic, horizontally long, or vertically long cross section by providing two sets of electrode pairs for focusing and diverging perpendicular to the advance direction of a charged beam pair and perpendicular to each other and forming the electrodes in the predetermined cross section shape. CONSTITUTION:An small electrode pair 4 facing in the (x) direction, a large electrode pair 5 facing in the (y) direction, and a power source 6 applying the voltage to both electrode pairs 4, 5 are arranged. The cross section shape of these electrode pairs 4, 5 is indicated by an rectangular hyperbola shown by a hyperbola x'<2>-(y'/alpha)<2>=+ or -a<2> obtained by multiplying the conventional coordinate value in the y-axis direction by alpha(optional constant), where 2a is the opening diameter and x'=x, y'=alphay. Accordingly, the shape of the opening can be made to coincide with the cross section shape of the incident beam, and the opening is utilized effectively.
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