Accuracy assessment of a linear birefringence measurement system using a Soleil-Babinet compensator

This article describes a method for assessing the accuracy of a new linear birefringence measurement system based on photoelastic modulator technology. We used a Soleil-Babinet compensator in the experiment and observed that its retardation varies significantly across the optical aperture. To use this compensator as a meaningful retardation standard, we fixed the beam position relative to the Soleil-Babinet compensator before and after its calibration. Our results show that the birefringence measurement system is capable of providing accurate measurements for linear retardation below 125 nm with a relative uncertainty below 1%. Experimental results support the fact that this birefringence measurement system is self-calibrating for measuring linear retardation. (C) 2001 American Institute of Physics.