Simple Invisibility Cloak From Off-The-Shelf Lenses
At the National Institute of Physics of the University of the Philippines, a team led by Dr. Nathaniel Hermosa created a Rochester cloak that does not impose conditions on the focal lengths. Using analytical ray tracing method, they recalculated the separation distances of lenses with arbitrary focal lengths.
The object being cloaked is the horizontal bar placed between the first and the second lens. The rising sun in the logo of the National Institute of Physics was not blocked by the bar
The experiments demonstrated the possibility of producing cloaking regions even when lenses have varied focal lengths because they can freely change the focal lengths. They have also found a way to reduce the length of the cloaking system.
The full article may be viewed at the link below:
Simple invisibility cloak from off-the-shelf lenses