Non-destructive testing of dielectric layers with defects

A microwave imaging method for non-destructive testing of dielectric surfaces beyond a layered media is presented. The method is based on the analytical continuation of the measured data to the surface under test through a special representation of the scattered field in terms of Fourier transform and Taylor expansion. Then the problem is reduced to the solution of a coupled system of non-linear integral equations which is solved iteratively via the Newton method with regularization in the least square sense. Numerical simulations show that defects having sizes in the order of λ/200 can be successfully recovered through the presented algorithm.