Observing correlated production of defects and antidefects in liquid crystals

We present observations of strength-one defects and antidefects formed in i sotropic-nematic phase transition of a thin layer of nematic liquid crystal s, using optical microscopy. We measure the widths of the distributions of net winding number in small regions, and determine the exponent characteriz ing the correlation between defects and antidefects to be 0.26 +/- 0.11, in very good agreement with the value 1/4 predicted by the Kibble mechanism f or defect production. We also describe a novel technique to determine the d irector distribution in observations of defect networks.