SIMULTANEOUS DETERMINATION OF THE BIREFRINGENCE, OPTICAL-ACTIVITY AND ROTATION OF THE INDICATRIX OF TRIGLYCINE SULFATE

The birefringence, rotation of the optical indicatrix and optical activity of triglicine sulphate (TGS) have been measured in the paraelectric and ferroelectric phases using a high-accuracy universal polarimeter (HAUP). The present measurements are compared with results already published in the literature and, surprisingly, many of them have been found to be in clear disagreement. Possible sources of systematic error are pointed out in the case of the optical activity measurements. The spontaneous parts of the different optical properties in the ferroelectric phase have been studied. These parts can be considered to develop under the exclusive influence of the spontaneous polarization. Simple relationships between the spontaneous optical quantities and the spontaneous polarization (quadratic for birefringence and indicatrix angle, and linear for gyration) are observed. Several electro-optic and electrogyration coefficients referred to the polarization are evaluated.