LAUSR

{Using two different approaches, we study imaging in the strong lens regime taking into account the effects of plasmatic environments on light propagation. First, we extend the use of a perturbative approach that allows us to quickly and analytically calculate the position and shape of the images of a circular source lensed by a galaxy. Such approach will be compared with that obtained from the numerical solution of the lens equations. Secondly, we introduce a 3-dimensional spheroidal model to describe the spacetime associated with the dark matter halo around the lens galaxy and an associated optical metric to incorporate the presence of the plasma medium. The (chromatic) deformation on caustic and critical curves and associated multiplicity of images is also analyzed for particular configurations.