Model of an extended jet-like polarized source (left) that is affected by the gravitational lens (right). The parameters for the macro lens are taken as for the Q0951+561 lens system. Small black lines show the distribution and orientation of the electric vector (lengths correspond to the rate of polarization as shown on the plots). The large arrows show only the orientation of the polarization vector, and the colours indicate the intensity in arbitrary units (blue showing smaller intensities).