The Coffee Cup Caustic
2005, installation
brass cylinder, metal arm, paper, torch, table.

In optics, a caustic is a curve of concentrated light, defined as the envelope of light rays reflected by a curved surface.A familiar caustic is the rainbow but another commonly observed example is the coffeecup caustic, which is the light pattern created on the top of a cup of coffee by strong light reflecting off the inside of the cup.

While caustics have been studied since antiquity, recent mathematical research by Dr. Brendan Guilfoyle (IT Tralee, Ireland) and Dr. Wilhelm Klingenberg (Durham University, England) has led to new mathematical techniques for computing the shape of these curves. These techniques have also lead to new discoveries about caustics and their symmetries.

This project involved generating caustics experimentally and comparing the results with the mathematical predictions. In the experiment the caustic is reproduced by reflecting a bright light off the inside of a polished brass cylinder and by varying the distance from the light source, the change of the shape of the reflected light was investigated. While for a coffee cup the only visible caustic is formed by a single reflection, with the brass cylinder it was possible to generate caustics formed by second, third and forth reflections.

Centerfold produced for Feint magazine and installation at Gallery for One, curated by Vaari Claffey, in collaboration with mathematician Brendan Guilfoyle.

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