Precise optical activity measurement of quartz plate by using a true phase-sensitive technique.

A method of considering the circular and linear birefringent properties of a material on the basis of circular and linear polarization eigenstates is presented theoretically and experimentally. A polarized common-path optical heterodyne interferometer with respect to both right-hand and left-hand circularly polarized light was set up. It was used in conjunction with a phase lock-in technique to measure the optical activity of quartz crystal in real time. The signal-to-noise ratio of the measured phase change caused by the lateral displacement of quartz cornus was 75, which corresponded to a measuring accuracy of 10(-7). This novel method, in which a true-phase-sensitive optical heterodyne interferometer is used, has higher detection sensitivity and higher immunity to environmental disturbances.