Why a Paraboloid?
The light coming
from a single star is essentially parallel because it is so far away.
Therefore, the ideal mirror will collect parallel rays so that they converge on
another point. Following is an informal explanation of how a parabola
accomplishes this. A parabola is only two-dimensional, but if it were rotated
around its axis, it would produce a paraboloid.
The graphs were generated with Apple Computer’s
Grapher. Diagrams were created with Microsoft word.