Here's the same cuere, but 'made' out of a glassy sort of material. You can't actually see it, but rather its effect on the light focused into it.
The big round thing off to the left is a perfectly-reflective ellipse with a light source at one focal point and the cuere at the focal point near the sliced-off end.

Rendered in Povray using 50 million photons

A comic detailing the workings of elliptical reflectors
http://xkcd.com/316/