Coffee Cup Caustic

You can move the light source and observe the changes in the reflected rays which form the caustic.

Tags: caustic, envelope, reflection, circle

Tchirnhausen's Cubic

The caustic formed by light projecting perpendicular to the axis of a parabola is called Tchirnhausen's Cubic. What happens when the light projects at some other angle?

Tags: Parabola, caustic