School of Physics Lecture Demonstration Manual

Oe-1 Light Pipe

Published: Wednesday 15 March 2006 - Updated: Monday 28 March 2011


To demonstrate total internal reflection.



Click on pictures to enlarge.

Light Pipe with Laser

Light Pipe

Light Pipe Diagram


Light Pipe


This demonstration consists of a curlicue shaped methyl methacrylate (Lucite) rod. This rod is used to demonstrate critical angle as well as total internal reflection. A light from a laser or a flashlight enters the rod at one end and strikes its walls at an angle greater than the critical angle of Lucite, and so it does not escape through it but is reflected between the walls of the rod until it reaches the other end. The effects are more striking as well as more visible to a large audience if a coloured light beam is used.

Safety notes

Electrical safety 

Laser safety 


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