Benjamin Titus with John Ruhl (project started January 2006)

Development and Testing of Millimeter-wave Half-Wave Plates (draft abstract)

In the project titled “Development and Testing of millimeter-wave Half-Wave Plates” we are testing a half-wave plate polarization rotator using birefringent sapphire crystals made by two different manufacturers. One of our goals is to determine if we can satisfy our needs using the less expensive crystals. We are testing the polarization properties as a function of frequency. Sapphire has a large index of refraction which leads to a large amount of reflection, this can cause unwanted interference. In order to reduce reflections we are also testing the performance of quarter-wave fused quartz anti-reflection coating as a function of frequency. We will take data and fit it to numerical models of half-wave plate/A.R coating systems. These tests are aimed at developing prototype half-wave plates that will be used by professor John Ruhl in future research on the Cosmic Microwave Background.