Abstract

Accurate determination of the thickness of nematic liquid crystal (NLC) films is essential in the study of the physical proper ties and use of these films. We demonstrate a novel interferometric method in which the birefringence of the NCL material is utilized. A probe laser polarized at an angle 45° off the incident plane is focused onto the sample at an arbitrary angle θ. The NLC film induces an optical path difference between the o-ray and the e-ray components of the transmitted light, and interference fringe spacing is used to calculate film thickness. This method is not affected by the substrate; it can be used to measure standard cells as well as NLC films with a free surface, i.e., NLC films with one surface exposed to the air.

© 1989 Optical Society of America