Real convex/ concave lens and mirror effect

I want to make an interactive 3d for teaching physics in my school. I need to make a convex lens effect like

http://blog.world-mysteries.com/wp-content/uploads/2011/03/convex_lens.jpg

and also concave mirror effect like

It’s OK either it must use BGE or must be rendered manually
Please give me any useful links if you could.