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Full-field optical measurement of curvatures in ultra-thin-film–substrate systems in the range of geometrically nonlinear deformations

Lee, Hansuk and Rosakis, Ares J. and Freund, L. B. (2001) Full-field optical measurement of curvatures in ultra-thin-film–substrate systems in the range of geometrically nonlinear deformations. Journal of Applied Physics, 89 (11). pp. 6116-6129. ISSN 0021-8979. doi:10.1063/1.1364650.

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This article describes coherent gradient sensing (CGS) as an optical, full-field, real-time, nonintrusive, and noncontact technique for the measurement of curvatures and nonuniform curvature changes in film-substrate systems. The technique is applied to the study of curvature fields in thin Al films (6 mum) deposited on thin circular silicon wafers (105 mum) of "large" in-plane dimensions (50.8 mm in diameter) subjected to thermal loading histories. The loading and geometry is such that the system experiences deformations that are clearly within the nonlinear range. The discussion is focused on investigating the limits of the range of the linear relationship between the thermally induced mismatch strain and the substrate curvature, on the degree to which the substrate curvature becomes spatially nonuniform in the range of geometrically nonlinear deformation, and finally, on the bifurcation of deformation mode from axial symmetry to asymmetry with increasing mismatch strain. Results obtained on the basis of both simple models and more-detailed finite-element simulations are compared with the full-field CGS measurements with the purpose of validating the analytical and numerical models.

Item Type:Article
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Rosakis, Ares J.0000-0003-0559-0794
Additional Information:©2001 American Institute of Physics. Received 2 October 2000; accepted 19 February 2001. The authors would like to acknowledge financial support through the Jet Propulsion Laboratory Center for Integrated Space Microsystems, System on a Chip (SOAC) program. Many helpful discussions with Dr. E. Kolawa of JPL are also acknowledged.
Subject Keywords:substrates; metallic thin films; aluminium; curvature measurement; deformation; internal stresses; finite element analysis; measurement by laser beam
Issue or Number:11
Record Number:CaltechAUTHORS:LEEapl01
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3706
Deposited By: Tony Diaz
Deposited On:29 Jun 2006
Last Modified:08 Nov 2021 20:11

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