This paper proposes a new arrangement for an interferometric laser‐speckle gauge. For the proposed set‐up geometrical inaccuracies are assumed. Therefore, we are looking for a sensor position, where the geometrical inaccuracies are having the smallest impact on the measurement result. For the measurement of an applied measurand vector to the observed specimen, we suggest a linear unbiased minimum variance estimator. Theory an measurement results using this estimator are shown for a specific measurement set‐up of the laser‐speckle strain gauge.
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<sup>1</sup> 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<sup>2</sup> . 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.