The Development and Application of Laser-optical Sensors for the Study of Macro- and Microdeformation Parameters of Advanced Materials

During the past years various non-contacting laser optical systems have been described which are used in various fields of mechanical testing and fracture research, mainly designed for the determination of two and three dimensional surface strain fields. For mechanical testing of materials at elevated temperatures it is frequently required to determine strain values with non-contacting optical methods, due to the fact that the conventional contacting strain measuring systems such as strain gauges or clip gauges cannot be applied at higher temperatures. Amongst the best known methods are holographic techniques, Moiré methods, laser speckle interferometry, laser extensometers and laser speckle correlation techniques. All these methods may be used for special purposes, however the adaptation of these high resolution optical systems to conventional testing devices are restricted due to various problems. A further application of non-contacting optical measurement systems was suggested during recent conferences both in Europe and the United States, indicating that there is a great demand to measure not only mechanical but also thermal properties of microspecimens used in micromechanics, -robotics and -electronics. In the framework of an international cooperative project (Materials Action COST 510) various laser systems were evaluated, developed and applied to test machines. The main objective of this international cooperation was to establis...(this text has been cut automatically)