Simultaneous determination of thickness and refractive indices of birefringent wafer by simple transmission measurement

摘要

We demonstrate a method for determining the principal indices of refraction and the thickness of a birefringent wafer. Simply, the light transmittance was measured while rotating the wafer. The directly transmitted beam makes interference with those multiply reflected between the surfaces as in a Fabry-Perot etalon, producing an interferogram as a function of angle of incidence. We applied this method to a LiNbO_3 wafer, determining the absolute values of ordinary and extraordinary indices with an uncertainty of 10~(-5). In addition to the measurement accuracy, the major advantages of our method are extreme simplicity and environmental robustness in the experiment.