Expérimental et théorique
Elastic wave investigations allow the evaluation of the mechanical properties in the media they propagated while being in a non-destructive regime. One possible method to extract such mechanical properties is through the measurement of the transmission matrix. This method has been already achieved successfully in optics and acoustics with transducer arrays but is more challenging to perform in laser ultrasonics. However, laser ultrasonics offer the advantage of a contactless measurement and a high spatial resolution that can be necessary in some media. The aim of this internship is thus to develop a novel approach that will tackle this difficulty in order to measure the transmission matrix of a sample in laser ultrasonics. To that end, the so-called wavefront shaping technique will be implemented with an SLM (spatial light modulator) to shape the excitation laser beam into various patterns in order to form different bases and acquire the transmission matrix. Its analysis will then reveal the media’s elastic properties. In parallel to this experimental work, theoretical work is necessary to estimate the transmission matrix dimensions needed for the characterization of the samples. The samples could vary from simple to complex media. This work can be extended with a PhD thesis, for which financing has been secured.