OPTICAL-PROPERTIES OF THE INTERFACE BETWEEN A TWISTED LIQUID-CRYSTAL AND AN ISOTROPIC TRANSPARENT MEDIUM

In the present Part 1, we calculate the optical properties of the inte rface between a twisted birefringent mesophase and an isotropic medium ; the interface is illuminated at normal incidence, in the direction o f the screw axis, with wavelengths situated in the well-known selectiv e reflexion band of the mesophase. The E' and E'' eigenmodes of the me sophase enable the transmitted E(t) and reflected E(r) vibrations to b e calculated : E(r) and E(t) have original properties induced by the c oupling between the dielectric reflexion (localized at the interface) and the selective reflexion (spread in the mesophase); their polarizat ion states depend on the incident polarization state and the direction of interface crossing. The particular cases described hereafter show that experiments can give the orientation of the helicoidal electrical field inside the mesophase (Part II).