Consider a point light source located at a point . The Catacaustic of a
unit Circle for the light at is the Nephroid
The Catacaustic for the light at a finite distance is the curve
and for the light on the Circumference of the Circle is the Cardioid
If the point is inside the circle, the catacaustic is a discontinuous two-part
curve. These four cases are illustrated below.
The Catacaustic for Parallel rays crossing a Circle is a Cardioid.
See also Catacaustic, Caustic
© 1996-9 Eric W. Weisstein
1999-05-26