Gravitational Lensing: Exploring exotic image forms and their applications

Gravitational lensing, essentially bending of light rays in a gravitational field, has now been an established fact for more than a century.  This field has seen rapid developments due to improvements in observations in the last half century.  It can be shown that gravitational lensing leads to formation of multiple images if certain conditions are satisfied.  Catastrophe theory can be used to further show that there are only five types of image formations possible with a single lens.  Focus of most studies so far has been on two of these five types as these are known to be stable.  I will summarise work that has been done on the remaining three types of image forms, of which two have now been observed in the sky.  I will also outline potential applications of these image forms and expectations for coming years.