Lateral resolution and transfer characteristics of vertical scanning white-light interferometers.
Lateral resolution and transfer characteristics of vertical scanning white-light interferometers.
复制标题
垂直扫描白光干涉仪的横向分辨率和传输特性。
作者：
Weichang Xie;P. Lehmann;J. Niehues
白光干涉仪广泛用于工业和科学应用中的高精度形貌测量。表征白光干涉仪的常用方法是假设表面振幅较小，从而产生由仪器传递函数 (ITF) 描述的线性传递特性。然而，众所周知的蝙蝠翼效应会产生系统误差，给 ITF 带来额外的非线性。在本文中，引入了一种模型来模拟由垂直扫描白光干涉仪获得的图像平面中的干涉图案，以克服小表面振幅的限制。对物体的不同高度位置重复模拟过程会产生图像堆栈，可以通过与实际测量数据相同的算法来分析该图像堆栈。仿真结果与实验观察结果一致：在某些情况下会出现蝙蝠翼效应，只要对矩形光栅结构进行光学解析，就可以获得正确的振幅。仿真和实验结果都提供了比基于线性系统行为的理论方法预测的带宽更宽的传输特性。
White-light interferometers are widely used for high-accuracy topography measurement in industrial and scientific applications. A common way to characterize a white-light interferometer is to assume small surface amplitudes resulting in linear transfer characteristics described by the instrument transfer function (ITF). However, the well-known batwing effect gives rise to systematic errors, causing extra nonlinearity to the ITF. In this paper a model to simulate an interference pattern in the image plane as it is obtained by a vertical scanning white-light interferometer is introduced in order to overcome the limitation of small surface amplitudes. Repeating the simulation procedure for different height positions of the object results in an image stack that can be analyzed by the same algorithms as real measurement data. The simulation results agree with experimental observations: the batwing effect occurs in certain situations and the correct amplitude of a rectangular grating structure can be obtained as long as the structure is optically resolved. Both simulation, as well as experimental results, provide transfer characteristics of broader bandwidth than predicted by theoretical approaches based on linear system behavior.