Interferometric characterization platform

The WaveSurf ultra-high frequency (1.2 GHz) laser vibrometry platform can accomplish various characterizations such as the characterization of:

  • Microelectromechanical systems (MEMS),
  • Surface wave electro-acoustic (SAW) devices,
  • Piezoelectric materials,
  • Thin films and functional coatings used in the fields electronics, optics, tribology, etc

As part of its various research, the TPIA (Transduction, Propagation and Acoustic Imaging) research group of the IEMN (UMR CNRS 8520)-IEMN - Valenciennes site carries out electrical, acoustic and optical characterizations of resonant microsystems with integrated transducers.

The aim is to study components and sensors that will be used in the medium and longer term in instrumentation and innovative characterization in various fields such as transportation, biotechnology, but also for industrial or consumer applications.

These components and sensors exploit high-frequency micrometric movements. This therefore requires characterization means that are very sensitive to very low vibrations (in the nanometer range) and in increasingly large frequency ranges.

Today, the IEMN - Valenciennes site has set up a WAVESURF interferometric platform with several devices:

The Polytec OFV-512 Device is a fiber interferometer that enables relative displacement measurements, meaning that it is possible to detect the displacement of a particular part on an otherwise vibrating structure. This first bench offers use in a range from 30 kHz to 24 MHz.

Polytec OFV-512 device

Example characterization

The Polytec UHF-120 Scanning Device allows operation in a much wider frequency range than previously possible as the bandwidth extends to 1.2 GHz.

This system allows to extend considerably the research in the field of characterization of layers and coatings and brings many perspectives of characterizations at the level of IEMN but also for the partners. It is also possible to realize displacement slicks and to create dynamic images corresponding to the global displacement of a structure.

Polytec UHF-120 device

In the electro-acoustic and micro-electro-mechanical fields, vibrometry measurements allow the detection and visualization of wave propagation and resonance modes. They also offer the possibility of detecting sources of unwanted losses and responses such as acoustic energy leakage, anomalous reflections or reciprocal coupling.

Within the framework of non-destructive testing (NDT), the studies carried out have made it possible to characterize metallic thin films and transparent sol-gel coatings:

  • Layer thicknesses: from 100 nm to a few micrometers,
  • Mechanical properties: Young's modulus, Poisson's ratio,
  • Estimation of residual stress gradients.

Examples of characterization

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