SURFACE DRIVEN TRANSITION IN A NEMATIC LIQUID-CRYSTAL CELL

Surface driven reorientation effects in a nematic liquid crystal cell caused by light-induced changes of the anchoring parameters were studi ed. Theoretical consideration of one-dimensional flat distributions of the director has shown that the director can undergo threshold reorie ntation between hybrid, homeotropic, and planar alignments as the anch oring energy varies continuously, The threshold reorientation takes pl ace when the reference and light-induced easy axes are perpendicular. In the one-elastic-constant approximation the light-induced transition was found to be of second order as shown by a critical increase of th e director thermal fluctuations in the vicinity of the transition poin t. These effects were experimentally studied in the cells containing 5 CB liquid crystal aligned by the photosensitive azo-containing polymer layer. (C) 1997 American Institute of Physics. [S1063-7761(97)01012-3 ].