| 摘要 |
PURPOSE: To suppress eddy currents and at the same time reduce drift of an electron beam caused by electromagnetic deflection by using a magnetic body, which has large electric resistance and a disaccomodation coefficient in a specific range, in the circumference of an electromagnetic deflection device. CONSTITUTION: A formed and contracted electron beam 1 is deflected by an objective lens part and the electron beam 1 is deflected on a sample face 5 in a prescribed position. A deflection range of a deflector 6 is surrounded with a pole piece consisting of objective lens coils 3, permalloy 2, and ferrite 4. Especially, 1 the deflector side of the objective lens coils 3 is constituted from ferrite 4 to reduce eddy currents generated in the pole piece part by electromagnetic deflection. Such ferrite 4 as having disaccomodation coefficient less than 1×10-5 and more than 1×10<-7> is used for reducing drift of the beam due to residue magnetic effect.
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