Hanford Observatory

May, 2005

Three Clover Park High School students explored LIGO physics in a hands-on fashion this year by constructing a benchtop Michelson interferometer. Thiwanka Samaranayake, Gregory Sarabia and William Ford (pictured above from left to right) used a set of plans created by LIGO scientist Fred Raab as a starting point, and, under the supervision of Clover Park math teacher Dave Olson, added several customized features to support their investigations.

The students used the interferometer to monitor the effects of thermal changes on the instrument's platform. Substituting steel for the wood base that the plans suggest, the students raised the platform well above the table top by placing supports underneath the center and the ends of the four extensions. The base between the beam splitter and the two end mirrors could be heated or cooled by the placement of a candle or dry ice under these portions of the steel. Shifts in the fringes of the Michelson's interference pattern indicated tiny changes in the beam path lengths as the metal expanded and contracted. The team used a larger-face beam splitter than the model listed in the plans, making alignment of the laser easier. They also borrowed a helium-neon laser from from physics instructor Elizabeth Devitt that produced nicely uniform beam spots. Gregory, William, Thiwanka and Mr. Olson spent a number of Saturday mornings assembling and troubleshooting the device, an investment that resulted in the students' successful display of the interferometer at a local science exposition.

Clover Park High School serves the community south of Tacoma, Washington and is a member of the Essential Schools Coalition.