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Optical Engineering • Open Access

Stress measurement of thin film on flexible substrate by using projection moiré method and heterodyne interferometry
Author(s): Kun-Huang Chen; Jing-Heng Chen; Hua-Ken Tseng; Wei-Yao Chang

Paper 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.

Paper Details

Date Published: 1 June 2016
PDF: 5 pages
Opt. Eng. 55(6) 064102 doi: 10.1117/1.OE.55.6.064102
Published in: Optical Engineering Volume 55, Issue 6
Show Author Affiliations
Kun-Huang Chen, Feng Chia Univ. (Taiwan)
Jing-Heng Chen, Feng Chia Univ. (Taiwan)
Hua-Ken Tseng, Feng Chia Univ. (Taiwan)
Wei-Yao Chang, National Chiao Tung Univ. (Taiwan)


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