Construction of Precise Analysis System of Conoscopic Images in Liquid Crystals

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1. We constructed a system to observe conoscopic images using a He-Cd laser, which surves one of shortest wavelength light sources.2. We constructed a program for analyzing conoscopic images using the 4x4 matrix method.3. We observed helix unwinding processes in ferroelectric liquid crystals by an electric field in detail utilizing the constructed system, and obtained the following results.3-1. The experimental results agree with the simulation results by the 4x4 matrix method based on the field-induced helix unwinding process by elastic theory. Particularly, negative biaxiality was observed by the application of an electric field and was theoretically explained.3-2. So far, the negative biaxiality was thought to be characteristic in ferrielectric phases and was used to identify the ferrielectrie phase. However, we clarify that the field-induced negative biaxiality is generally observed in the ferroelectric phase and cannot be used to identify the ferrielectrie phases.3-3. We found that the previous conoscopic observation in MHPOBC, in which the antiferroelectric phase was first confirmed, was made using unsaficient field strength, that cannot induce complete helix unwinding. We reobserved the conoscopic images in detail by applying high fields saficient to induce complete helix unwinding. As results, we concluded that the helix unwinding process in MHPOBC cannot be explained only by considering ferroelectric interaction between the applying field and the polarization.