the reconstruction of cylinders with complex media is investigated.The forward scattering problem is first analyzed by using the FD MEI(Finite Difference Measured Equation of Invariance) method
then the objective function is constructed in terms of the difference between the computed scattering fields and the measured fields
and finally the objective function is minimized based on the conjugate gradient method and variable metric method.The solution results in the reconstruction of the media of the cylinder.In the optimization procedure
the gradient of the objective function is rigorously derived.Several reconstruction examples are presented
where the reconstruction of a conducting cylinder is based on the measured Ipswich.