| 摘要 |
PURPOSE:To obtain good resolution over the whole region of a target surface by applying an auxiliary electrode plate with a small aperture for limiting the electron beam diameter to the end plate section on the G2 electrode side of a G3 electrode. CONSTITUTION:When each voltage of 300V and 800V is applied to a G2 electrode 9 and a G3 electrode 10, a focusing type electron lens is generated between both electrodes and an electron beam emitted from a cathode 1 advances in a convergence path. The current density passing through a small aperture 11a for limiting the beam diameter is increased comparatively and the angle of divergence is reduced comparatively. This indicates that the operating voltage of a G1 electrode and a crossover point are deviated to the negative side and the cathode side, respectively. That is, the current density and cathode load in the crossover point are reduced and the angle of beam divergence becomes narrow. As a result, high resolution can be obtained in the peripheral section of a target electrode surface through the captioned pickup tube is of a UPF type. |
