In 1990 I wrote a proposal to the Mizzou Alumni Fund for Faculty Instructional Development to get an exhibit built in the lobby of the Physics Building at the University of Missouri. The purpose of the exhibit is to demonstrate several phenomena associated with the polarization of light. The exhibit consists of a display cabinet with three shelves. The back panel is translucent and back lit by several lamps. On the shelves are several items whose optical properties are affected by the direction of the polarization of light that passes through them. Since the lamps produce unpolarized light, these effects may not be discernible by a viewer unless a polarizer is used to differentiate them. In a classroom the classical method is to use a sheet of polarizer, such as sunglasses, and to rotate the sunglasses by 90 degrees to observe these effects. In this exhibit the rotation is automated by means of a a large (36″) wheel that supports a sheet polarizer, allowing only one direction of polarized light to be seen by the viewer at any given moment. Since wheel rotates continuously, the direction of polarization changes continuously, allowing the viewer to see the changing optical effects produced by the items in the shelves. This exhibit has been in operation since it was built in 1991. Additional exhibits based on the reflection and refraction of light were added over the years.
The lamps trace the history of lighting. In the early year or two we used “long life” incandescent bulbs mounted in shoplight holders. Needless to say, these bulbs “died” every few months, and we were always on the lookout for a tall, slim person who could wedge themselves between the cabinet and the wall in order to change the bulbs, The availability of cheap screw-in florescent lamps helped this issue by changing the lifetime of the bulbs from a few months to a a couple of years. The display underwent a thorough overhaul around 2010, when the lights were replaced by LED panels.
I thank the Physics Machine shop – Cliff Holmes, the late Sam Potts, Rod Schlozhauer and Warren Stiefelman for building the polarization display and maintaining it over the years.
