Detection of surface microstructure changes by electronic speckle pattern interferometry

Electronic speckle pattern interferometry is elaborated in such a way that spatially resolved image decorrelation can also be measured. While retaining the typical ESPI set-up for deformation measurements, a speckle correlation formalism is implemented based on the phase-shift method. In many practical situations decorrelation is directly related to surface microstructure changes of a test specimen. Feasibility and restrictions of the method are illustrated by measurements of water-induced changes at the surfaces of natural stones and by monitoring microbiological activity on stones. Copyright (C) 1996 Elsevier Science Ltd.