Uncertainty of height information in coherence scanning interferometry
Uncertainty of height information in coherence scanning interferometry
复制标题
相干扫描干涉测量中高度信息的不确定性
DOI：
10.1117/12.889796
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
D. Broschart
中科院分区：
文献类型：
--
作者：
J. Seewig;T. Böttner;D. Broschart
宽带光源相干扫描干涉测量法（简称白光干涉测量法）是除共聚焦技术外最流行的测量表面形貌的光学原理之一。与相干干涉法相比，宽带光源在理论上可以得到明确的相位信息。本文讨论了相关图在空间域和频域的性质。与理想相关图的所有偏差都用一个附加相位项表示。讨论了德格鲁特频域分析和希尔伯特变换两种方法中高度信息的不确定性。在频域分析中，不确定度用cram<s:1> - rao界来量化。论文的第二部分讨论了相关图的相位计算，这是获得高垂直分辨率所必需的。由于包络函数经常被扭曲，相位跳变导致高度信息不明确。特别是，这种效应可以在测量粗糙表面时观察到。
Coherence scanning interferometry CSI with a broadband light source (short known as white light interferometry) is, beside the confocal technique, one of the most popular optical principles to measure surface topography. Compared to coherent interferometry, the broadband light source leads, theoretically, to an unambiguous phase information. The paper describes the properties of the correlogram in the spatial and in the frequency domain. All deviations from the ideal correlogram are expressed by an addition phase term. The uncertainty of height information is discussed for both, the frequency domain analyse (FDA) proposed by de Groot and the Hilbert transform. For the frequency domain analyse, the uncertainty is quantified by the Cramér-Rao bound. The second part of the paper deals with the phase evaluation of the correlogram, which is necessary to achieve a high vertical resolution. Because the envelope function is often distorted, phase jumps lead to ambiguous height informations. In particular, this effect can be observed measuring rough surfaces.