Characterization of micromaterials using laser speckles

This document shows the theory and set-up of a non-contact measurement strain gauge, which measures translation and strain of a mechanically or thermally loaded specimen. The measurement gauge basically consists of a light source emitting a collimated monochromatic laser beam illuminating the specimen and two CMOS line- scan cameras, which are arranged symmetrically about the incident laser beam picking up speckled reflection. The cameras are recording the granular laser speckles in specific time-intervals and the subsequent images are processed by an algorithm1 implemented in GNU C. As a result one obtains accurate information about changes in the state of strain and rigid body translation the specimen undergoes2 . Furthermore experimental results are introduced. The dilatation of a piezo-stack, the elastic modulus of a thin copper wire and the elastic modulus of a soldering joint are investigated.