Vibration Analysis at Microscale by Talbot Fringe Projection Method

This work focuses on the implementation of a structured light projection technique for the analysis of the 3D vibration modes of microsamples. The Talbot image of a Ronchi grating is projected onto the sample surface passing through one of the objective tube of a stereomicroscope thus realising a fringe projection system at a micrometric scale. An aluminium cantilever beam PZT-driven into harmonic vibration served as test sample for investigating the possibility to get the full-field vibration modes of micro-objects. An automated Fourier transform analysis of the fringe patterns was performed to obtain the full-field time-resolved profile information of the sample at each frame delivered by a high-speed camera with a micrometric resolution. A straightforward procedure for retrieving resonance frequency for different modes and vibration amplitudes along the whole sample surface was implemented. The great sensitivity and the full-field capacities of the proposed experimental procedure allow to put in evidence differences between real and theoretical behaviours hence could be extremely useful for designing and testing structural dynamic response of microstructures and micro-electro-mechanical Systems.