Speckle correlation used for measuring microstructural changes in paper

Abstract

In this paper the use of laser speckle correlation as a mean to measure the micro-structural changes in paper exposed to a changing environment will be presented. Of particular interest will be changes in humidity and crack propagation. Speckle correlation is a technique that calculates the local structural change in a speckle pattern as the object deforms in real time. The response of the technique is the local rate of micro-structural change in the material. Speckle correlation is hence a complement to other speckle metrology techniques. The paper starts with a short introduction to speckle correlation but will focus on applications of the technique on paper. Results from studies of wetting of printing paper at the flock scale, dynamic response in copy paper when exposed to a sudden change in humidity and crack propagation in a notched sheet of Kraftliner are included.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.