A deep learning approach to inverse medium scattering: Learning regularizers from a direct imaging method

Abstract: This paper aims to solve numerically the two-dimensional inverse medium scattering problem with far-field data. This is a challenging task due to the severe ill-posedness and strong nonlinearity of the inverse problem. As already known, it is necessary but also difficult numerically to employ an appropriate regularization strategy which effectively incorporates certain a priori information of the unknown scatterer to overcome the severe ill-posedness of the inverse problem. In this paper, we propose to use a deep learning approach to learn the a priori information of the support of the unknown scatterer from a direct imaging method. Based on the learned a priori information, we propose two inversion algorithms for solving the inverse problem. In the first one, the learned a priori information is incorporated into the projected Landweber method. In the second one, the learned a priori information is used to design the regularization functional for the regularized variational formulation of the inverse problem which is then solved with a traditional iteration algorithm. Extensive numerical experiments show that our inversion algorithms provide good reconstruction results even for the high contrast case and have a satisfactory generalization ability.