| 摘要 |
An electron-optical system devised so as to generate a pseudoeparallel micro electron-beam coverging at a converging angle of 1 x 10<-><3> radian. The system comprises a condenser lens assembly (3, 4) and an asymmetric objective lens (6) whose smaller field gradient side is directed to the condenser lens assembly (3, 4). In another electron-optical system achieved by modifying the above system, the converging angle of the electron beam is made variable with an additional objective lens (8) inserted between the condenser lens assembly (3, 4) and the asymmetric objective lens (6). Theconversion angle can be varied by varying the conversion powers of both the objective lenses (6, 8). <IMAGE>
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