Optical measurement of surface deformation

An electronic camera, which is synchronized with the oscillation via a digital phase shifter, is targeted on this pattern. By recording a reference frame e.g. at the neutral position of the wing as well as a second frame in the deflected position and comparing both, the displacement vectors of the dots can be calculated by means of correlation analysis. Hence the translation and the deformation of the examined surface are obtained. For qualitative preview this calculation can be done in real-time, so that the vectors are directly depicted on the screen. By using the digital phase shifter, the movement of the object and the corresponding vector fields can be displayed in real-time as slowly as desired (slow motion effect). To get real three-dimensional information about the movement and the deformation of the investigated surface, a stereoscopic camera setup consisting of two cameras targeted on the same dot pattern from different positions i.e. under different viewing angles can be used.