| 摘要 |
<p>The gun according to present invention has a triple electrodes part as a source of the electron beam, and prefocusing and main lens part for focusing and accelerating the beam. The prefocusing lens part includes a plurality of focusing electrodes (21,22,23,24) for forming at least one quadrapole lens in which the intensity of vertical lens is weaker than that of horizontal lens. According to the present invention, the effect of the spherical aberration to the beam entering the main lens can be reduced. <IMAGE></p> |
