Nonlinear thermotropic and thermo-optical behaviour of planar oriented textures in nematic liquid crystals at phase transitions

thermotropic, thermo-morphologic and thermo-optical properties of the planar oriented nematic liquid crystals have been investigated for large temperature interval and especially for the direct nematic - isotropic liquid and the reverse isotropic liquid - nematic phase transition regions. temperature dependences of the optical transmission, absorption coefficient and optical birefringence for both heating and cooling processes were obtained. nonlinear thermotropic and thermo-optical behaviour and temperature hysteresis for the optical transmission, absorption coefficient and optical birefringence at the phase transitions has been found.