Light Pipe, Step Index Fiber
In light pipes and step index fibers, rays enter a tube (being either solid
or hollow) and reflect
from the walls in an indeterminate number of times until they emerge. The end
surfaces may have any form (spherical, aspherical, Fresnel, etc.) and may also be
Light pipes are formed by extruded surfaces and are handled by the sequential surface
model. Circular or rectangular cross sections are supported. All forms may be tapered.
Rectangular light pipes can also be sheared (see figure below). Violation of total internal reflection (TIR) in
solid pipes is taken into account.