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Proceedings Paper

Micro-profile measurement of a transparent coating using windowed Fourier transform in white-light vertical scanning interferometry
Author(s): Suodong Ma; Chenggen Quan; Rihong Zhu; Lei Chen
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Paper Abstract

Owing to free of the phase ambiguity problem, white-light vertical scanning interferometry (WLVSI) is commonly used to inspect surface profiles of objects, especially for the micro-profile measurement of microelectromechanical systems (MEMS) devices. Although numerous algorithms have been proposed for the white-light interference signal analysis, most of them focused only on test objects with a single reflective surface. In this paper, a technique to measure the micro-profile of a transparent coating using windowed Fourier transform in WLVSI is described. A windowed Fourier filtering (WFF) operation is first adopted to roughly estimate the local peak positions of a recorded interference signal. Subsequently a least-square estimation based on the retrieved phase values of a filtered signal is separately applied into previously extracted local peak positions to achieve more accurate micro-profile results. The thickness of the coating can be finally estimated by the retrieved reflective surfaces. Experimental works, conducted on a flat plate and a MEMS device with a transparent coating on its substrate, demonstrate the validity of the proposed method.

Paper Details

Date Published: 15 October 2012
PDF: 6 pages
Proc. SPIE 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 841725 (15 October 2012); doi: 10.1117/12.970532
Show Author Affiliations
Suodong Ma, Nanjing Univ. of Science and Technology (China)
Chenggen Quan, National Univ. of Singapore (Singapore)
Rihong Zhu, Nanjing Univ. of Science and Technology (China)
Lei Chen, Nanjing Univ. of Science and Technology (China)


Published in SPIE Proceedings Vol. 8417:
6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; Libin Xiang; Sandy To, Editor(s)

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