Published online by Cambridge University Press: 15 March 2002
Triglycine sulphate, $(\rm NH_2CH_2CO_2H)_3\cdot H_2SO_4$ (TGS), is a ferroelectric crystal widely used in optical properties studies, phase transitions theory as well as test for experimental techniques. Lead monohydrogen phosphate, PbHPO4 (LHP), is a typical representative of the family of ferroelectric schultenites, suitable in testing microscopic theories of ferroelectricity. In this work the so-called high-accuracy universal polarimeter (HAUP) has been used to determine the natural anisotropy in the birefringent crystalline sections (010), obtaining the temperature dependence of optical anisotropy magnitudes of the crystal: gyrotropy, birefringence and optical indicatrix rotation. Our HAUP technique also permits to investigate the electro-optic (EO) coefficients associated to the phases above and below phase transition temperatures.