Digital birefringence measurement using the cross-correlation method

A digital system for measuring a small amount of birefringence or small changes in existing birefringences is presented. The apparatus is based on a data-acquisition system for a spectral-contents analysis. The use of cross-correlation techniques significantly reduces the data-processing time and permits measurement of the dispersion of the stress-optical coefficient of materials. The accuracy is of the same order as in the modulation techniques. The sensitivity of this method could be changed by changing the order of interference. A comparison is made with other existing polarization methods.