LIGHT DEFLECTION PHENOMENA IN ANTIFERROELECTRIC LIQUID-CRYSTALS

Characteristic light deflection phenomena in antiferroelectric chiral smectic liquid crystals were investigated. Strong deflected light beam s were observed in parallel alignment cells in the antiferroelectric p hase at the electric field induced phase transition to ferroelectric s tate. The origin of the light deflection phenomenon was confirmed not to be diffraction due to a periodical change of refractive index cause d by helical structure which is common to chiral smectic liquid crysta ls, but to be reflection and refraction at boundaries between coexisti ng phases or domains. Incident angle dependence of the angle of deflec tion was numerically analyzed on the basis of the method applied to th e case of ferroelastic crystals, and a qualitative agreement between t he calculated results and the experimental ones was obtained. Similar light deflection phenomena were observed also in ferroelectric phase a nd ferrielectric one at zero electric field. Molecular alignment struc ture in those phase or domains are discussed.