Optical interference microscopes are widespread in topography and roughness measurement on the micro- and nanoscale. In spite of a wide range of scientific and industrial applications, systematic deviations between the measured and the real surface topography occur in certain situations, e.g. at edges or steep flanks. We present a numerical model considering the properties of the measurement instrument as well as the surface structure to be measured in order to get new insights into the physical dependencies of these deviations. The computation is based on a rigorous simulation of the scattered near field combined with a Fourier optics treatment of the image formation in the measurement instrument. In this study, the near fields are calculated with an open-source finite element method (FEM) software and a commercial finite difference time domain method (FDTD) software. The numerical results are compared with an analytical Kirchhoff approach and measurements. The main intention of this paper is to introduce the modelling and point out possible fields of application. In further studies, this model could be extended to 3D and parameter dependencies of systematic deviations, such as the material of the measurement object and the NA of the measurement instrument, could be investigated.

中文翻译：

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基于严格近场计算的光学干涉显微镜系统表面高度偏差的二维建模

光学干涉显微镜广泛用于微米和纳米尺度的形貌和粗糙度测量。尽管有广泛的科学和工业应用，但在某些情况下，例如在边缘或陡峭的侧面，测量的和真实的表面形貌之间会出现系统偏差。我们提出了一个数值模型，考虑了测量仪器的特性以及要测量的表面结构，以便对这些偏差的物理依赖性有新的了解。该计算基于对散射近场的严格模拟，并结合测量仪器中图像形成的傅立叶光学处理。在这项研究中，近场是使用开源有限元法 (FEM) 软件和商业有限差分时域法 (FDTD) 软件计算的。将数值结果与解析基尔霍夫方法和测量结果进行比较。本文的主要目的是介绍建模并指出可能的应用领域。在进一步的研究中，该模型可以扩展到 3D，并且可以研究系统偏差的参数依赖性，例如测量对象的材料和测量仪器的 NA。