Multitasking Polariscopes, To Go

PHOENIX, Ariz., March 16 -- Ken Cardell, a graduate student at the University of Arizona Optical Sciences Center, recently fashioned a polariscope from common objects (paint stirrers, clothespins, sawed-off film canisters, popsicle sticks, photocopies of a protractor and some hot melt glue), neatly solving a major challenge for students in Russell Chipman's optics course: how to hold and rotate several polarizers at one time.

Ken Cardell demonstrates his portable multitasking polariscope.

Students use Cardell's free-standing polarizers, which can be operated with one hand, for take-home experiments and problems. A polariscope enables viewing of a sample between polarizers and phase shifting retarders to determine the angular direction of polarization of incoming light and how the polarization changes as it passes through materials. Polarization analysis applications include chemical analysis of solutions, mineral identification, surface properties of materials, internal stress analysis and liquid crystal display technology.

"These cheaper devices emulate the high-quality, expensive, metal machined instruments used in research, but they are more easily replaced or fixed with commonly available components," he said. In this design, the wood clothespins and popsicle sticks provide just the right amount of friction -- the polarizers can be moved easily, but do not wobble once they are in position. Substituting a wooden ruler for the paint stirrer would allow items to be placed at specified separations, he said.

Cardell previously worked at the National Optical Astronomy Observatory, making inexpensive optics kits for elementary school pupils, and found that less-precise demonstration optic mounts could be made from wood and plastic and distributed for educational purposes.

Professor Russell said, "We were all surprised and delighted when Ken brought a box of these polariscopes to class and handed them out. The students were delighted because he gave them a nice optical system that lets them explore the concepts of the class and check their polarizer calculations. I was delighted because now I can give them harder problem sets to solve."

For more information, visit: www.optics.arizona.edu