Corrosion monitoring with speckle correlation.
The changes in the microtopography of a metal surface during a corrosion process are measured by decorrelation of the scattered speckle fields under coherent illumination. For that purpose a quantitative relation between the decorrelation of the scattered light fields and the rate of corrosion is established in a theoretical model, based on the statistics of phase and reflectivity changes of point scatterers at the surface. The speckle fields are recorded by a CCD camera and processed numerically in a computer, yielding the standard deviation of the topography changes with nanometer sensitivity. From the analysis of a series of images taken at equal time intervals during the corrosion process, the degree of interrelation among subsequent topography changes is calculated.
Fricke-Begemann
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Department of Physics, Carl von Ossietzky University Oldenburg, D-26111 Oldenburg, Germany. frick@uwa.physik.uni-oldenburg.de
Gülker
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Hinsch
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Wolff
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