Development of novel method for measuring optical activity of solids and its applications

Although measurement of the optical activity of solids has been impossible for the 180 years since its discovery by Arago (1811), we have developed a method called HAUP (high accuracy universal polarimeter), which enables one to measure simultaneously optical activity, birefringence, and rotation of the indicatrix of any crystals, even those belonging to the monoclinic and triclinic systems. Thus HAUP has opened new research fields in condensed matter science. This article reviews our applications of the HAUP method to studies on several unresolved problems in this science. It includes an understanding of the origin of structurally incommensurate phases of some ferroelectrics, the determination of the correct crystal symmetries of the transparent PLZT ceramics, first measurements of anisotropic gyrations in helical polymers, and optical activity of HTSC. It is important to note that these problems could be solved only by making use of the crucial property of optical activity.