Multi-Physics Inversion of Acoustic and Electromagnetic Wave Fields

Multi-modality or multi-physics imaging is gaining interest beacuase it overcomes the limitations of a single imaging modality, as each modality typically suffers from its own application specific limitations. Different imaging techniques are developed to combine the outcome of both modalities; varying from image fusion up to the usage of prior information obtained from one imaging modality and used as input for the other one. In this work an alternative approach is presented. The method employs a multi-physics Born inversion algorithm where structural similarity is used as regularization parameter to align the acoustic and electromagnetic contrast interfaces with each other. To align the interfaces the gradients of the acoustic and electromagnetic contrast functions are used. Two approaches are tested successfully on a synthetic profile; one where the cross-product of the two gradients and one where the gradient differences are considered. Both approaches work but the gradient-difference approach outperforms the cross-gradient one. Overall, it is shown that multi-physics Born inversion both approaches reveals details in the electromagnetic contrast function that would have been missed by only employing electromagnetic inversion. This improvement is obtained at the cost of an increase in computational complexity compared to single modality inversion.