Zhong Yi, Gross Herbert
Appl Opt. 2018 Feb 20;57(6):1482-1491. doi: 10.1364/AO.57.001482.
It is well known that freeform surfaces are used to improve the resolution in systems without rotational symmetry. For Scheimpflug systems, the tilted object plane leads to variant magnification in the system imaging. Thus, the system suffers from non-rotationally symmetric aberrations, non-uniform resolution, and non-uniform intensity distribution. In this paper, the paraxial imaging condition of Scheimpflug systems is discussed. From the classical viewpoint, the aberration theory is used to understand, balance, and improve the system performance for variant object distance. For large object distance shift, it is necessary to apply freeform surfaces. With the initial system design method based on Gaussian brackets, the starting configuration of a Scheimpflug system with large object distance shift is obtained. Based on the extension of the Nodal aberration theory concerning the aberrations of freeform surfaces, the rules of selecting the freeform surface position in the system are introduced. By adding two freeform surfaces far away from the pupil, the aberrations are effectively corrected in the Scheimpflug system. The aberrations along the field are decomposed and represented using Zernike fringe polynomials to show the improvement of uniformity and resolution. This work provides insight into Scheimpflug system design with freeform surfaces.
众所周知，自由曲面用于提高非旋转对称系统的分辨率。对于施密特系统，倾斜的物平面会导致系统成像中的放大率变化。因此，该系统存在非旋转对称像差、分辨率不均匀和强度分布不均匀的问题。本文讨论了施密特系统的近轴成像条件。从经典观点出发，利用像差理论来理解、平衡和改进系统在不同物距下的性能。对于较大的物距偏移，有必要应用自由曲面。通过基于高斯括号的初始系统设计方法，获得了具有大物距偏移的施密特系统的初始配置。基于关于自由曲面像差的节点像差理论的扩展，介绍了在系统中选择自由曲面位置的规则。通过在远离光瞳的位置添加两个自由曲面，有效地校正了施密特系统中的像差。沿着视场的像差被分解并用泽尼克条纹多项式表示，以展示均匀性和分辨率的提高。这项工作为使用自由曲面的施密特系统设计提供了见解。
