Zygo interferometer for measuring refractive index of photorefractive bismuth silicon oxide (Bi12SiO20) crystal

An application of the Zygo system for measuring the refractive index of opt ical materials such as bismuth silicon oxide (BSO) having a higher value of the refractive index than that of glass is presented. The setting accuracy is found to be of the order of 1 mu m in the Zygo phase measuring interfer ometer. The mean value of refractive index of BSO crystal measured by the i nterferometer for several samples of thickness in the range of 3-9 mm is 2. 542 at a wavelength of 632.8 nm. The accuracy of measurement is +/-0.002. I t is possible to achieve an accuracy of +/-0.0003 for a sample of thickness of 30 mm in the measurement of refractive index due to high setting accura cy of the Zygo system. (C) 1999 Elsevier Science Ltd. All rights reserved.