Abstract

The objective of this thesis is the development of a laser-optical strain and displacement measurement system, which calculates mechanical or thermal strain and the superposed rigid-body-motion from the motion of a laser-speckle-pattern originating from a small illuminated surface spot. The system makes use of objective speckle patterns and therefore does not depend on imaging optics.

The work comprises amongst others an overview of literature relevant for this area of research, the important physical principles, a detailed description of the measurement principle and also an error analysis of the entire system, which cannot be found in the currently available literature.

Additionally one chapter is dedicated to signal-processing, which is necessary for the calculation of the speckle-pattern motion.

Furthermore the applicability of the speckle-strain-sensor is shown by means of various experiments having been accomplished with the developed measurement system and which are of interest to the area of material physics. Besides experiments for the measurement of the coefficient of thermal expansion, tensile-tests with thin foils and fibres down to the micrometer range were performed.