Title:

Gravitational Lensing



Jean Surdej
Institute of Astrophysics and Geophysics, Liège University
Belgium



Abstract:

After briefly reviewing the history of gravitational lensing since the
early thoughts of Newton in 1704 until the serendipitous discovery of
the first gravitational lens system by Walsh, Carswell and Weymann in
1979, we recall the basic principles of atmospheric and gravitational
lensing.  We then describe and use a simple optical gravitational lens
experiment which has the virtue of accounting for all types of image
configurations observed among presently known gravitational lens
systems. This experiment also accounts for dust extinction in lensing
galaxies, the formation of giant luminous arcs, etc.  We shall show
how it is possible to use gravitational lensing as a cosmological and
astrophysical tool. Results obtained for the case of the quadruply
imaged quasar RXS J1131-1231, using the method of backwards ray
tracing, will be shown. Finally, we shall briefly present the 4m
International Liquid Mirror Telescope project in the context of a
photometric monitoring of multiply imaged quasars.