Electro-optic and thermo-optic effects in liquid crystals

Abstract
The twisted nematic electro-optic effect has become widely used as a low-voltage, low-power display in watches and calculators; however, it is only one of the many optical effects found in the various liquid crystal phases. Despite this wide variety, certain features of operation are general. Liquid crystals are birefringent, which, together with their ability to align on solid surfaces, allows the construction of thin layers with optical properties reminiscent of single solid crystals. The more common display devices use anisotropic electrical properties to produce electro-optic effects that are seen by using polarized light, scattering, or the absorption of light. Thermooptic effects can be produced by varying the temperature of the liquid crystal in the vicinity of a phase transition, and are used in thermometry, thermography, and display devices.