Digital image correlation (DIC) is a method for measuring the surface displacements and displacement gradients in materials under deformation. During the calculation, the traditional DIC method directly uses the intensity values of compared images and does not take out-of-plane error into account. However, in scanning probe microscopy measurements, the recorded z-direction intensity value is a sum of the real topography surface of the sample and any longitudinal nonlinear deformation of the piezoelectric tube. In order to improve the calculation accuracy of the displacement fields, an improved DIC method is performed by which the real topography is separated from the z-direction drift error. Two unknown parameters related to out-of-plane drift error are introduced in the correlation coefficient. The in-plane displacements between two compared images are then calculated pixel by pixel using the real topography data extracted from the raw data, with the drift error removed. This method is tested by applying it to two pairs of atomic force microscopy images along the fast and slow scan directions.
Proceedings Title: 2009 Proceedings of the ASME International Manufacturing Science and Engineering Conference
Conference Dates: October 4-7, 2009
Conference Location: West Lafayette, IN
Conference Title: 2009 ASME International Manufacturing Science and Engineering Conference
Pub Type: Conferences
digital image correlation, Newton-Raphson iteration, scanning probe microscopy, piezoelectricity tube, hysteresis