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Decorrelation of Laser Speckle Patterns for Crack-Tip High Strain Field Determination and Use in Brittle-Ductile Fracture Analysis

  • J. Scott Steckenrider
  • James W. Wagner
Chapter
Part of the Review of Progress in Quantitative Nondestructive Evaluation book series

Abstract

The uses of laser speckle photography are widespread in mechanics and metrology[1][2]. Most, if not all, of the applications of laser speckle involve the comparison of two correlated speckle patterns of a given field before and after some perturbation to the system has occurred. From the relative displacement of the correlated patterns either Young’s fringes or isothetic fringes may be produced when the specklegram is processed[3]. It is from these fringes that one quantitatively determines the speckle spacing from which such information as displacement and displacement gradient (strain) can be calculated. However, if the displacement, displacement gradient, surface tilt, or surface out-of-plane displacement is excessive, or if the surface morphology changes, the correlation of the speckle patterns is lost and the fringes are either distorted or simply no longer visible. In this case the speckle patterns are said to be decorrelated and accurate quantitative information about changes to the system is no longer available.

Keywords

Speckle Pattern Displacement Gradient Bend Specimen Laser Speckle Surface Tilt 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    R. K. Erf (ed.), “Speckle Metrology.” Academic Press, New York, 1978.Google Scholar
  2. 2.
    M. Francon, “Laser Speckle and Applications in Optics.” Academic Press, New York, 1979.Google Scholar
  3. 3.
    I. Yamaguchi, Fringe formation in speckle photography, J. Opt. Soc. Am. A, 1, 81, (1984).CrossRefGoogle Scholar
  4. 4.
    J. C. Dainty (ed.), “Laser Speckle and Related Phenomena.” Springer-Verlag, New York, 1975.Google Scholar
  5. 5.
    D. W. Li and F. P. Chaing, Decorrelation functions in laser speckle photography, J. Opt. Soc. Am. A, 3, 1023, (1986).CrossRefGoogle Scholar
  6. 6.
    R. Jones and C. Wykes, “Holographic and Speckle Interferometry.” Second Edition, Cambridge University Press, Cambridge and New York, 1989.Google Scholar

Copyright information

© Springer Science+Business Media New York 1990

Authors and Affiliations

  • J. Scott Steckenrider
    • 1
  • James W. Wagner
    • 1
  1. 1.Center for Nondestructive EvaluationThe Johns Hopkins UniversityBaltimoreUSA

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