Résumé
•Digital Volume Correlation in soft viscoelastic media.•Geometric correction for perspective and refraction effects.•Spatiotemporal filtering for harmonic component extraction.•Multi-frequency measurements in 3D heterogenous elastography phantoms.
This work presents a novel method for measuring the 4D displacement fields within phantom materials typically used for elastography experiments. This method allows independent validation of the time-harmonic displacement and deformation measurements commonly used in elastography methods, and also allows the experimental measurement of complex systems such as flow through flexible vessels within viscoelastic media. The optical scanning tomography and digital volume correlation techniques used for this method are presented in detail, including the geometric and imaging corrections used to ensure accurate results. In addition, a spatiotemporal filtering approach to extract the frequency domain harmonic content of the measured temporal data is presented. Experimental results are analysed in multiple phantom configurations and via comparison with numerical simulation using finite element methods. Overall, the method presented here offers, repeatable, highly resolved images of the displacement field even in heterogenous phantom configurations with good agreement to theory. These results show that this method has the potential to serve as a valuable tool for the development and validation of advanced elastography methods, capable of characterizing the complex, multi-scale and multi-physics behaviours typically observed in biological tissues.