| 摘要 |
PURPOSE:To have a charged beam radiated on a target of radiation without being influenced by the aberration of a lens means on one side, by controlling said lens means so that the charged beam can radiate the target of radiation in a focused state. CONSTITUTION:A charged beam 2 coming from a charged beam source 1 is radiated on a target of radiation 4 disposed on a bench 3, and electro-static type lens menas 25 and 5 with controllable focal distances are arranged in order. In this case, an aperture plate 35 having an aperture 36 is interposed between the lens means 25 and 5. And the charged beam 2 is so arranged as to radiate the aperture plate 36 including its aperture 36 by use of the lens means 25. And the charged beam 2, thus obtained by such radiation through the aperture 36 is arranged to radiate the target of radiation 4 on the bench 3 via the lens means 5 in a focused state and following the pattern corresponding to the pattern of an aperture 27. Thus, the charged beam 2 can be radiated on the target of radiation 4 without being influenced by the aberration of the lens means 5.
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