Ultrasonic Tomography Using Full Waveform Inversion

Team Members: Jing Rao, Stefan Kollmannsberger, Ernst Rank

Funding:  Alexander von Humboldt Foundation under grant number 1022809., DFG Grant KO-

Running period: AvH: 05.2019 - 05.2021 DFG: 2020-2023 Grant No. KO 4570/1-1 and RA 624/29-1

Project description

Quantitative imaging can provide quantitative estimation of physical properties such as velocity, density and attenuation. The ability to reconstruct physical properties from wave measurements is very valuable in many applications as it could allow diagnostic methods with high sensitivity. For example, numerous defects are reflected in acoustic velocity variations, and thus velocity reconstruction from wave measurements can be used for defect detection. Based on this concept, ultrasonic tomography provides a promising alternative for defects/inclusions diagnosis. The key thing in ultrasonic tomography is the applicability and usefulness of accurate and high resolution algorithms for reconstructions of physical properties. In this project, a quantitative ultrasonic imaging approach based on elastic full waveform inversion (EFWI) is developed for accurate reconstructions of physical properties in isotropic and anisotropic structures. The forward model is computed in the frequency/time domain by solving a full-wave equation in a 2D/3D elastic model, accounting for mode conversions and multiple scattering. The inversion is based on local optimization of a waveform misfit function between modeled and measured data.