静电聚焦同心球系统的成像电子光学B章:近轴横向色差与几何横向球差

Imaging Electron Optics of Electrostatic Focusing Concentric Spherical System Part B:Paraxial Lateral Chromatic Aberration and Geometrical Lateral Spherical Aberration

在A章基础上,进一步研究两电极静电聚焦同心球系统的轴上点电子光学横向像差。研究表明,对于成像电子光学系统,由光阴极发射的电子所形成的图像弥散,其轴上点的图像弥散由近轴横向色差与几何横向球差两部分组成,这证明了在静电聚焦同心球系统中,阴极透镜的二级近轴横向色差即Recknagel-Apцимович公式普遍成立。研究了宽电子束与细电子束之间轴上点横向像差之差异,最后讨论了两电极同心球系统向近贴聚焦系统过渡的特例。

On the basis of the part A,this paper goes further study the electron optical lateral aberration of axial points of the bi-electrode electrostatic focusing concentric spherical system.It shows that the image diffusion of axial points formed by the electrons emitted from the photocathode in an electron optical system is composed of two parts:the paraxial lateral chromatic aberration and the geometric lateral spherical aberration.This confirms that in the electrostatic focusing concentric spherical system,the second order paraxial lateral chromatic aberration of the cathode lens,that is,the Recknagel-Apцимовичformula,is generally valid.This paper also studies the differences of lateral aberrations of axial points between the wide electron beam and the narrow electron beam.Finally,a special case of transit of the proximity focusing system from the bi-electrode electrostatic focusing concentric spherical system is also investigated.