Constructing the Catacaustic of an Ellipse -Parallel Rays
- Irina Boyadzhiev
A light source at infinite distance from the ellipse produces some parallel light rays (in yellow). The rays are reflected by the ellipse. If the rays have more than one intersection point with the ellipse, they are reflected at both points. The reflected rays and their continuations are shown in light blue. Definition: The envelope of the reflected rays by the ellipse is called the catacaustic of the ellipse (also caustic).
- Drag the first slider - numberRays to change the number of light rays.
- Drag the second slider - α to change the angle between the rays and the major axis of the ellipse.
- To experiment with the catacaustic, select different values for the semi-major and semi-minor axis. Select different angles α. Look also at the special case a=b.