Subpixel microscopic deformation analysis using correlation and artificialneural networks

Microscopic deformation analysis has been performed using digital image cor relation and artificial neural networks (ANNs). Cross-correlations of small image regions before and after deformation contain a peak, the position of which indicates the displacement to pixel accuracy. Subpixel resolution ha s been achieved here by nonintegral pixel shifting and by training ANNs to estimate the fractional part of the displacement. Results from displaced an d thermally stressed microelectronic devices indicate these techniques can achieve comparable accuracies to other subpixel techniques and that the use of ANNs can facilitate very fast analysis without knowledge of the analyti cal form of the image correlation function. (C) 2001 Optical Society of Ame rica.