Characterization of Micro-Materials 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 algorithm implemented in GNU C. As a result one obtains accurate information about changes in the state of strain and rigid body translation the specimen undergoes . 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.