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The scanning laser vibrometer or scanning laser Doppler vibrometer is an instrument for rapid non-contact measurement and imaging of acoustic pressure waves and vibration.
Fields where they are applied include automotive, medical, aerospace, micro system and information technology as well as for quality and production control.
The operating principle is based on the Doppler effect, which occurs when light is back-scattered from a vibrating surface. Both velocity and displacement can be determined by analyzing the optical signals in different ways. A scanning laser vibrometer integrates computer-controlled X,Y scanning mirrors and a video camera inside an optical head. The laser is scanned point-by-point over the test object’s surface to provide a large number of very high spatial resolution measurements. This sequentially measured vibration data can be used to calculate and visualize animated deflection shapes in the relevant frequency bands from frequency domain analysis. Alternatively, data can be acquired in the time domain to, for example, generate animations showing wave propagation across structures. In contrast to contact measuring methods, the test object is unaffected by the vibration measuring process.
Univ.-Prof. DI Dr. Martin Schagerl
The Laser-scanning-vibrometer is used for the analysis of structural dynamics and acoustics by high frequency measurements of the surface velocity of mechanical components (up to 25MHz, only out-of-plane).
- Highly sensitive infrared laser
- Close-Up unit for small range precision measurements
- Time domain data processing and illustration
- Frequency domain data processing and illustration, FFT frequency discretisation up to 816200 lines
Methods & Expertise for Research Infrastructure
The LSV is used to do research in the field of structural health monitoring (SHM).
A research field that uses systems of sensors to monitor mechanical structures to permanently evaluate its integrity.
In particular the LSV is used to validate hypotheses and simulation results related to dynamic SHM methods (methods based on steady vibrations and guided ultrasonic waves) by measuring surface velocities of specifically excited structures.
The measurements are done in both, time and frequency domain.