After recalling the basic principles underlying the formation of atmospheric and gravitationally lensed mirages, we describe a simple optical lens experiment which accounts for all types of image configurations observed among presently known gravitational lens systems. We shall also report on a recent systematic search for multiply imaged quasars based upon observations carried out with Gaia and in the near future with the 4m International Liquid Mirror Telescope.
Jean Surdej earned his Physical Sciences degree in 1975, followed by a Ph.D. in Astrophysics in 1979, and an academic habilitation in 1991, all from the University of Liège, Belgium, Faculty of Sciences. He initially pursued his career under the Belgian National Fund for Scientific Research (F.R.S.-FNRS), achieving the title of F.R.S.-FNRS Research Director in 1995. In 2002, he transitioned to an academic path, becoming a Full Professor at the University of Liège in 2007. He has also served as a visiting professor at Adam Mickiewicz University (Poznan, Poland) and as VAJRA Adjunct Faculty at ARIES (Nainital, India). Since October 2017, he has expanded his research, teaching, and training activities internationally, including in Qatar, India, Chile, and Poland. He is actively involved in the 4m ILMT project in ARIES and has regularly visited ARIES since 2012.