| 摘要 |
PURPOSE:To enable a high resolutional characteristic to be realized by sufficiently reducing the spherical aberrations of main electron lenses while maintaining the distances between the three electron guns of an in-line-type electron gun structure at the same level. CONSTITUTION:An in-line-type electron gun structure has an electron-beam forming part consisting of, at least, negative G1 and G2 electrodes 21 and 22, as well as a G3, a G4, a G5 and a G6 electrode 23-26 which accelerate and focus an electron beam discharged by the electron-beam focusing part. It is provided with a multi-stage focusing electron lens system which forms three stages of main focusing electron lenses at the facing parts between the G3 and the G4 electrodes, between the G4 and the G5 electrodes and between the G5 and the G6 electrodes. In the structure 2, the electrode aperture (Hc34) of the forward two stages of main electron lenses which are located on the negative electrode side of a central electron gun 2G is made larger than the electrode aperture (Hs34) of both side electron guns, and the electrode aperture (Hs56) of the third-stage main electron lens which is located on the electron-beam discharge side of the both side electron guns is made larger than the electrode aperture (Hc56) of the central electron gun 2G, so that the spherical aberration of fucusing electron lens stages of each electron gun which have an increased aperture can be reduced. |
