| 摘要 |
PURPOSE:To improve resolution by forming a cylinder-shaped correction electrodes of two outer electron guns among three in-line electron guns with magnetic material of high permeability and forming that of the central electron gun with nonmagnetic material, and further changing the aperture of outer gun electrodes from that of the central gun electrode. CONSTITUTION:For cylinder-shaped correction electrodes 23B, 24B installed in a penetration hole area portion of electrodes 23, 24 forming a main electron lens of three in-line electron guns, correction electrodes 23Bs, 24Bs of the outer electron guns are made of a permalloy, while correction electrodes 23Bc, 24Bc of the central electron gun are made of a stainless steel, and apertures of the correction electrodes of the outer electron guns are formed larger than that of the correction electrode of the central electron gun. Further, a focusing coil 28 is arranged on the outside area of a container 2 corresponding to the range of correction electrodes 23Bs, 23Bc to form an electromagnetic focusing lens 29. As a result, focusing characteristics of an electrostatic electron lens may be largely improved by two outer electron guns, leading to remarkable enhancement of resolution. |
