Abstract
In the first of several experiments using liquid crystals, a sample of N-(p-methoxybenzylidene)-p-butylanailine (MBBA) was examined by means of a "sandwich cell". The sample was examined under a microscope while an AC voltage was applied to it. At voltages above the threshold voltage, a fingerprint pattern was observed. This pattern of parallel lines is known as Williams' Domains. At voltages considerably higher than the threshold voltage for Williams' Domains, the phenomenon of dynamic scattering is observed.
Electrooptic Experiments on Liquid Crystals
In this series of experiments, an electrooptic apparatus was constructed from a flashlight, two polarizers and a detector. Through these experiments, the properties of transmission, light scattering, polarization, birefringence, index of refraction and optical rotation were explored using two types of liquid crystal displays (LCD's), the twisted nematic (TN) liquid crystal and the polymer dispersed liquid crystal (PDLC).
The Advanced Liquid Crystalline Optical Materials Consortium of Kent State University in association with Case Western Reserve University and Akron University publish an educational newsletter on liquid crystals. The newsletters include general information about liquid crystals and short experiments which demonstrate their properties. I completed this series of experiments and found them to be extremely informative and entertaining. What follows is a brief summary of these experiments along with background information related to each set of exercises.
Here is a list of books, web sites, etc. to get you going if you're interested in liquid crystals!
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