Focusing-Based Newton Solution for Electromagnetic Inverse Scattering Problems

This article presents a new physical linearization technique for inverse scattering problems (ISPs) and an algorithm that integrates this technique with the Newton method. It is shown that focusing the incident field reduces the nonlinearity of the problem, enabling successful reconstructions in high resolution. In addition, the algorithm effectively integrates the focusing approach into the Newton method. With this contribution, the multiple scattering effect due to the whole investigation domain is suppressed, and thus, nonlinear and ill-posed nature of the problem is mitigated. Also, the algorithm eliminates the need for an accurate initial guess since it constructs the required initial guesses through the iterative process. Several numerical tests demonstrating the effectiveness of the focusing concept and the algorithm are conducted. It is shown that the proposed method provides successful reconstructions in which the conventional multi-incidence Newton solution fails. Besides, not only are the reconstruction errors substantially reduced, but the computation times are also decreased by approximately a factor of 3. In addition, the proposed method performs robustly against noise up to 20%.