Determining elliptical polarization of light from rotation of calcite crystals

This paper demonstrates the non-uniform circular rotation of calcite crystals in an elliptically polarized laser mode. Birefringent calcite crystals respond in predictable ways to polarization. A laser mode with high ellipticity (approaching circular polarization) causes a calcite crystal to rotate at a higher rate than that with a low ellipticity (approaching linear polarization). The polarization orientation of the laser mode also directly affects the instantaneous crystal rotation. We place calcite crystals in a trapping region, and observe their behavior under different polarization modes. Measurements of rotation rates, orientation, and motion of calcite crystals are made by synchronizing information from video images and a quadrant photodiode. These measurements are then compared with predicted values.