Light tamers.

The article discusses images created through the control of an optical phenomena, called caustics. Topics include an overview of caustics, which are patterns created by the refraction or reflection of light by curved surfaces, such as the bright lines of light on the bottom of a swimming pool, a demonstration of Mark Pauly and colleagues' technique for refracting light in a specific way by shaping the surface of perspex (plexiglass) to produce an image of computer scientist Alan Turing, and a history of the use of mirrors to create complex patterns of light. A diagram illustrating how a precisely shaped piece of glass refracts and focuses light so that it projects an image onto a screen is presented.