研制大面积阴极磁聚焦分幅变像管。在2∶1电子光学倍率下, 研究单磁透镜和双磁透镜成像的像场弯曲。基于光学透镜成像原理, 假设成像面形状不随激励微调而改变, 推导了离轴点最佳成像位置与激励变化的近似关系式, 并由此提出一种测量并减小像管像场弯曲的方法; 借助Matlab编程模拟了像管各离轴点的最佳成像位置, 拟合得到成像曲面方程, 并利用所提出的像场弯曲测量方法进行了测试验证。结果表明, 在一定视场范围内, 计算机模拟与实验测试结果比较接近。单、双磁透镜下的最佳成像面均为旋转抛物面, 但双磁透镜成像像场弯曲比单磁透镜有明显的改善。

A large cathode magnetic-focusing framing image converter tube is designed and developed. The field curvatures of single magnetic lens and double magnetic lens systems are investigated at electron optical magnification of 2∶1. Based on optical lens imaging principle, the approximate relational expressions of the imaging excitation variation with the best image positions of the off-axis object are derived in the cases of single magnetic lens and separated double magnetic lens systems. It is assumed that the shape of image surface does not change with excitation in a certain scope. Accordingly, a method of field curvature measurement and decrease is proposed. Then, by virtue of Matlab programming, the best image positions for off-axis point objects are simulated, and the image surface equations are fitted, which are experimentally verified by use of the proposed method of field curvature measurement. It is showed that computer simulations agree with the experimental results within a certain field of view. Both of the best image surfaces of two systems are paraboloids of revolution. But the field curvature of double magnetic lens system is obviously smaller than that of single magnetic lens system.