Phase Transitions in Nematic and Cholesteric Liquid Crystals

具有定向有序而不具有位置有序的液晶有几种不同的形式，其中大多数是近年来才发现的。这些结构包括一些相当奇特的结构，比如在高光活性胆固醇中发现的立方晶格蓝相和无定形雾相，以及在某种肥皂溶液中首次发现的双轴向列相。它提出了一系列的光学实验设计来探测这些材料的相变。他们的目标是有助于更好地理解系统所表现出的许多关键现象，例如这些具有张量阶参数的系统。

Liquid crystals which possess orientational ordering but no positional ordering come in several different forms, most of which have been discovered only in recent years. These include some rather exotic structures, such as the cubic lattice blue phases and the amorphous fog phase found in cholesterics of high optical activity, and the biaxial nematic first discovered in a certain soap solution. It presents a series of optical experiments designed to probe the phase transitions of these materials. Their goal is to contribute to a better understanding of the many varieties of critical phenomena exhibited by systems, such as these, having tensor order parameters.