Determination of the director pretilt angle at liquid-crystal layer boundaries by polarimetric and crystal rotation methods in the same cell

The pretilt angle of the director at the liquid crystal–glass interface is determined with the polarimetric and crystal rotation methods. The polarimetric method has been modified with the aim of increasing the measurement accuracy. The results obtained with the modified polarimetric method are verified with the use of reference plane-parallel iceland spar plates with known pretilt angles of the optical axes. It is shown that the pretilt angles found with the crystal rotation and modified polarimetric methods coincide within the measurement accuracy.