Optical measurements of self-induced oscillations

High speed digital holographic interferometry is used to measure the self-induced mechanical oscillations produced by frequency signals near the first natural resonance mode of a rectangular polyester membrane. The external excitation produces very low mechanical amplitude levels in the membrane. This non-invasive optical technique has high temporal and spatial resolution allowing large data acquisition and hence allowing the processing of thousands of recorded images acquired in a CMOS camera set at 5000 frames per second (fps).

Research highlights► High speed digital holographic interferometry is a very powerful optical technique that can be used to measure very low amplitude mechanical vibrations such as those produced by self-induced oscillations. ► This research opens new possibilities to high spatial resolution optical dynamic measurements in the order of hundreds of nanometers in non destructive optical testing, for example, for the characterization of some physical variables of semisolid objects over dynamic conditions. ► It can be said that we have been able to measure non linear phenomena in a complete cycle of mechanical vibration for the first time.