A technique for measurement of pretilt angles arising from alignment layers

A well-controlled, reproducible alignment with or without a pretilt angle is a basic need for the development of any kind of liquid crystal display. We have built an optical set-up based on the crystal rotation method. With this system we can measure the pretilt angle in non-twisted liquid crystal samples. Presentation of the experimental set-up and first results of these measurements (obtained with a precision of 0.3 degrees) are given for several compounds and alignment layers.