Speckle interferometry uses the interference characteristics of electromagnetic waves. It is based on the fact that an optically rough surface appears granulated when it is lit by an coherent light (laser). This phenomenon is called a speckle and the individual grains are termed speckle.
After each load step, the reflected light is captured with an CCD camera. In this example the Department of Structural Design of the Eindhoven University of Technology, Faculty Bouwkunde, has used the ESPI SD-30 (3D-ESPI) in tests on masonry and presents their results.
Keywords: High sensivity deformation and strain measurement
Video holography is a remote sensing and non-destructive measurement technique for the detection of deformations and strains. This technique is demonstrated with a chipboard specimen during a tensile test where the deformation behaviour in the whole measuring area can be observed in real-time until fracture.