A teleidoscope is a kind of kaleidoscope. Unlike other kaleidoscopes, teleidoscopes have a lens and an open view, so they can be used to form kaleidoscopic patterns from objects outside the instrument, rather than from items installed as part of it. It was invented by John Lyon Burnside III.

The lens at the end of the tube is not an optical requirement, but protects the internals of the teleidoscope from objects which a child might insert. A spherical ball lens is often used. An advantage of using a sphere is that it will not press flat against the object being viewed, which would block all light and result in no image being seen.

In addition to building a teleidoscope with mirrors, it is possible to make a digital teleidoscope using ray tracing techniques.

Links

* Teleidoscope explanation from the Brewster Society