High-Accuracy Contactless Method for Determination of Chemical Composition of Lithium Niobate Crystals by Their Birefringence

摘要

A high-accuracy method for determining the chemical composition of non-stoichiometric lithium niobate crystals is proposed based on precise measurements of birefringence of thin substrates using the laser ellipsometry in transmission. It is shown that, for compensators made of LiNbO_(3), this method allows one to monitor the ratio Li/(Li + Nb) with an accuracy of up to approx10~(-8) at lambda velence 0.6328 (mu)m. The accuracy is limited by temperature fluctuations of the crystal.