In quasi-optical systems, the beam distortion and the cross-polarisation caused by the offset reflectors get a lot of attention. Also, the distortion was thoroughly studied in previous works. In this study, the authors give the detailed derivations of exact and approximate expressions of cross-polarisation and some simple explanations about energy conversion between co- and cross-polarisations in two-dimensional multi-reflector systems based on Gaussian beam mode analysis (GBMA). In addition two dual-reflector systems with different structures are used to verify the correctness and accuracy of GBMA comparing with physical optics (PO) in commercial software GRASP10. Furthermore, the authors fabricate one of these two systems and give experimental results. Then, they propose a fast analysis algorithm based on the vector addition method to reduce the computation time by eliminating the redundant modes. The efficiency of the proposed fast algorithm is illustrated by the number of modes and the calculation time for each reflection in a tri-reflector system. In addition, the authors also present the computation time of PO in GRASP10 as a reference. With the application of the fast algorithm, the computational efficiency is improved and increases with the number of reflections.

中文翻译：

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快速二维高斯光束模式分析方法的理论和实验验证

在准光学系统中，由偏移反射器引起的光束畸变和交叉偏振引起了很多关注。另外，在以前的工作中对畸变进行了彻底的研究。在这项研究中，作者提供了基于高斯光束模式分析（GBMA）的正交偏振的精确和近似表达式的详细推导，以及有关二维多重反射器系统中共偏振和交叉偏振之间的能量转换的一些简单解释。 。另外，与商业软件GRASP10中的物理光学（PO）相比，使用两个具有不同结构的双反射器系统来验证GBMA的正确性和准确性。此外，作者制造了这两个系统之一，并给出了实验结果。然后，他们提出了一种基于矢量加法的快速分析算法，通过消除冗余模式来减少计算时间。提出的快速算法的效率由三反射器系统中每个反射的模式数量和计算时间来说明。此外，作者还介绍了GRASP10中PO的计算时间，以作为参考。随着快速算法的应用，提高了计算效率，并随着反射次数的增加而提高。