电子光学系统的计算机辅助设计(CAD)一般只能由给定的边界条件(几何结构和电参数)计算其有关参量。近几年来,关于如何从给定参量确定电子光学系统结构的问题已日益受到重视。M.Szila’gyi于1977年提出了用动态规划法来搜索球差系数最小时的静电透镜(或磁透镜)的轴上电位(或磁感应强度)分布的方法,但是它并不能给出最终的透镜结构,而必须用实验方法来模拟确定符合这轴上电位(磁感应强度)分布的电子光学系统。本文提出的单纯形法(Simplex Method)的最优化设计方法能够直接搜索目标函数——球差系数最小的电子光学系统的最终结构。作为一个实例,本文叙述了应用该法求得的扩展场透镜的最佳结构和电参数,在像方焦距不增大 Computer-aided design (CAD) of electronic optical systems generally can only calculate its relevant parameters from given boundary conditions (geometry and electrical parameters). In recent years, the issue of how to determine the structure of an electro-optical system from a given parameter has drawn increasing attention. In 1977, M. Szila’gyi proposed a method of using dynamic programming to search for the on-axis potential (or magnetic flux density) distribution of an electrostatic lens (or magnetic lens) with the smallest spherical aberration coefficient, but it does not give the final Lens structure, and experimental methods must be used to simulate the electron optical system that determines the distribution of potential (magnetic induction) distribution on this axis. The simplex method proposed in this paper can directly search the final function of the objective function, the final structure of the electron optical system with the smallest spherical aberration coefficient. As an example, this paper describes the best structure and electrical parameters of the extended field lens obtained by this method. The focal length of the image does not increase