Surface scattering and the 3D transfer characteristics of optical profilers
Surface scattering and the 3D transfer characteristics of optical profilers
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光学轮廓仪的表面散射和 3D 传输特性
DOI：
10.1117/12.2556878
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Coupland J
中科院分区：
文献类型：
--
作者：
Coupland J
从工程表面散射的电磁辐射携带与表面形貌相关的信息，表面测量仪器如相干扫描干涉仪，共焦和焦点变化显微镜。虽然这些仪器的操作原理看起来完全不同，但它们的性能从根本上受到用于测量散射场的照明和光学器件的性质的限制，并且在实践中可以非常相似。在最近的工作中，我们试图用三维线性系统理论来表征光学仪器的性能。通过这种方式，测量场通过3D点扩散函数或等效地在频域中表示的传递特性与表面形状相关。本文阐述和扩展了这一概念，检查传统的接触式计量和非接触式光学计量使用相同的线性系统框架。线性系统理论的讨论与参考对象的测量具有变化的表面梯度和不连续性，在这两种情况下，可以采用类似的方法来测量和补偿的传输特性，使用球形校准文物。最后，我们考虑从原始测量估计表面形状的非线性步骤。我们讨论了逆形态滤波的情况下，接触测量和反演使用严格的矢量散射模型的潜力，以提高测量使用光学轮廓仪。
Electromagnetic radiation scattered from an engineering surface carries the information that is related to surface topography by surface measuring instruments such as coherence scanning interferometers, confocal and focus variation microscopes. Although the operating principles of these instruments appear quite disparate, their performance is fundamentally limited by the properties of the illumination and the optics used to measure the scattered field and can be remarkably similar in practice. In recent work we have attempted to characterize the performance of optical instruments using 3D linear systems theory. In this way the measured field is related to the surface form by the 3D point-spread function or equivalently the transfer characteristics expressed in the frequency domain. This paper illustrates and extends this concept by examining traditional contacting metrology and non-contacting optical metrology using the same linear systems framework. Linear systems theory is discussed with reference to the measurement of objects with varying surface gradient and discontinuities and in both cases, similar methods to measure and compensate the transfer characteristics using spherical calibration artefacts can be employed. Finally, we consider the non-linear step of estimating the surface form from raw measurements. We discuss inverse morphological filtering in the case of contacting measurements and inversion using a rigorous vector scattering model with the potential to improve measurements using optical profilometers.