Two-Dimensional Birefringence Profiling of Optical Wafers by Differential Phase Retardation Method

Abstract
We have proposed a new method of observing two-dimensional birefringence profiles in optical crystal wafers irrespective of physical thickness distribution by differentiating phase retardations of two orthogonal polarizations. The birefringence profiling of LiNbO3 wafers of 125 mm diameter has been demonstrated and inhomogeneous structures with a small birefringence of approximately 1×10-5 have been visualized successfully. It is suitable for not only material analysis in research but also a rapid non-destructive inspection of wafers in production lines.