| 摘要 |
PURPOSE:To remove the chromatic aberration due to deflection by so winding a plurality of lens coils provided along the optical axis separately that magnetic fields generated by each lens coil are opposing each other. CONSTITUTION:An electron lens 4 is constituted by providing lens coils 7, 8 in a yoke 6 along the optical axis Z. A deflecting coil 9 is provided in the electron lens 4, and a sample 5 is placed below. The lens coils 7, 8 are so wound that magnetic fields generated by each lens coil are opposing each other, and are so designed that the integration of optical axis component of the magnetic fields between the deflection center Z0 to the sample level Zs (sum of area S1 and S2) is to be zero. Thus the rotational direction component of aberration due to deflection can be made zero. |
