ABSTRACT Kochanek, Christopher AST-9401722 Gravitational lenses, particularly radio ring lenses, can provide important new information on the structure of E and S0 galaxies. This information is independent of traditional dynamically studies, and it has radically different systematic problems. The greatest advantage of lens models is that they directly measure the gravitational field in the distant galaxy, thereby avoiding all the systematic assumptions needed to determine the mass distribution from dynamical studies. This research will use algorithms for inverting radio lenses to systematically invert the radio lenses using families of mass models to determine the mass distributions in the inner 5-10 kpc of the lens galaxies. In cases where one sees the lens galaxy, the MMT will be used to make dynamical measurements for comparisons. This will allow a direct calculation of the anisotropy of the velocity dispersions, and a direct calculation of the mass to light ratio. There will also be algorithmic improvements in the inversion method. ***
