Camera focuses on a coin behind a polarizing filter and a quarter wave plate
Purpose:To illustration the polarization of reflected light from a conductive object, and the effects of a quarter wave plate
Description:In this demonstration, a polarizing filter and a quarter-wave plate are mounted together on a vertical support, the polarizer on top, with light passing between them. Underneath the quarter-wave plate, a coin or other reflective, conductive object is places on a light-colored nonconductive background (such as a piece of paper) to be seen easily. A camera is mounted looking down through both filters, and a small lamp is used to illuminate the system from the side.
The interacting of the polarization shift of the quarter wave plate and of the reflection from the conductor means that when the light that has reflected off the conductor returns again to the upper polarizer, it is polarized 90 degrees off from the original state; so with the correct alignment, the coin appears black, while the background remains white.
Instructor should plan to provide own coin if possible.
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Last modified on Wednesday, 02 September 2020 16:45