A PSD-based method for measuring the thickness and refractive index properties of optical plates

This study develops a non-destructive measurement system based on a position sensing detector (PSD) and a laser interferometer for determining the thickness and refractive indices of a birefringent optical wave plate. The proposed metrology system provides the ability to measure the refractive index of thick optical plates by determining the refraction angle. The experimental results obtained for the refractive index values of a commercially available wave plate are accurate to within 0.007. Furthermore, the error in the wave plate thickness measurement is just 2.37 μm. Hence, the metrology system presented in this study provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent wave plates.