Full-field measurement of nonuniform stresses of thin films at high temperature.

AML, Department of Engineering Mechanics, Tsinghua University, Beijing, China.
Optics Express (Impact Factor: 3.53). 07/2011; 19(14):13201-8. DOI: 10.1364/OE.19.013201
Source: PubMed

ABSTRACT Coherent gradient sensing (CGS), a shear interferometry method, is developed to measure the full-field curvatures of a film/substrate system at high temperature. We obtain the relationship between an interferogram phase and specimen topography, accounting for temperature effect. The self-interference of CGS combined with designed setup can reduce the air effect. The full-field phases can be extracted by fast Fourier transform. Both nonuniform thin-film stresses and interfacial stresses are obtained by the extended Stoney's formula. The evolution of thermo-stresses verifies the feasibility of the proposed interferometry method and implies the "nonlocal" effect featured by the experimental results.

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