MBL meets OPTIMESS 2019 lecture:
"State of the Art of Laser-Doppler-Vibrometry and Future Trends"
Vibrations reveal characteristics of technical and natural systems. Therefore, vibration measurements are important for many engineering tasks. Tactile vibration sensing suffers from influences by the coupling to a seismic mass, limited bandwidth, and the additional masses of the sensors attached to the specimen surface. Laser-Doppler-vibrometry (LDV) obtains the information by evaluating the Doppler frequency shift of a laser beam scattered at the specimen and is free of these drawbacks. LDV has a wide range of possible applications due to a high bandwidth (up to the GHz range), a high intensity dynamic (up to 160 dB/√Hz), and the capability to obtain operational deflection shapes by scanning the measuring laser beam over the specimen surface.
Although the technology is already well established for vibration analysis, recent developments have advanced the potential of LDV substantially. For example, multipoint vibrometers allow the measurement at multiple points simultaneously in order to study deflection shapes and resonance frequencies in mechanical systems during warm-up, in systems with statistic excitation by friction, or in biological self-excited systems (e.g. vibrations of the cardiovascular system). A further example is the detection of Doppler-shifted light scattered in 3D from a single laser spot. This is achieved by detecting light scattered in different directions simultaneously. 3D motions of tiny mechanical structures like MEMS can be measured with picometer resolution.
The talk gives an overview of the current state of the art of laser-Doppler vibrometry and identifies future trends for LDV. Finally, the talk concludes the current research projects on laser vibrometry at the TU Clausthal.