Stress measurement of thin film on flexible substrate by using projection moiré method and heterodyne interferometry

Kun-Huang Chen; Jing-Heng Chen; Hua-Ken Tseng; Wei-Yao Chang

doi:10.1117/1.OE.55.6.064102

1 June 2016 Stress measurement of thin film on flexible substrate by using projection moiré method and heterodyne interferometry

Kun-Huang Chen, Jing-Heng Chen, Hua-Ken Tseng, Wei-Yao Chang

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Optical Engineering, Vol. 55, Issue 6, 064102 (June 2016). https://doi.org/10.1117/1.OE.55.6.064102

Abstract

We propose a stress measurement system based on a projection moiré method and heterodyne interferometry for thin films on a flexible substrate. In the measurement setup, a CMOS camera in which every pixel can receive a series of heterodyne moiré signals by using a continuously relative displacement with a constant velocity is used. Furthermore, the phase of the optimized sinusoidal curve and the surface profile of the flexible substrate are determined using a least-squares sine fitting algorithm. The thin-film stress is obtained by representing the cross-sectional curve of the surface profile by using a polynomial fitting method, estimating the resultant curvature radii of the uncoated and coated substrates, and using these two radii in the corrected Stoney formula. The proposed measurement system has the advantages of high accuracy, high resolution, and high capacity for substrates with high flexibility and a large measurement depth.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Kun-Huang Chen, Jing-Heng Chen, Hua-Ken Tseng, and Wei-Yao Chang "Stress measurement of thin film on flexible substrate by using projection moiré method and heterodyne interferometry," Optical Engineering 55(6), 064102 (1 June 2016). https://doi.org/10.1117/1.OE.55.6.064102

Published: 1 June 2016

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