The twisted nematic field effect switches a nematic liquid crystal between a twisted optically rotating state and a largely field-aligned state. With adiabatic optical following in a twisted nematic and crossed polarizers aligned to the two planar surface directors, a quarter-turn cell passes light at low voltage and suppresses it at high voltage. A rear reflector permits reflective operation with little power expended on light generation.
When the birefringence separation of optical propagation constants is large compared with the spatial rate of rotation of the optical axes, light with linear polarization in a local eigenpolarization follows the twisting nematic director. Thickness alone is insufficient if birefringence vanishes. Strong field alignment along the propagation direction suppresses the transverse optical anisotropy and hence the quarter-turn polarization rotation.
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Twisted nematic field effect refers to a configuration commonly used in liquid crystal displays (LCDs) that involves a specific arrangement of liquid crystal molecules. In particular, the "twisted nematic" (TN) structure is characterized by the orientation of liquid crystal molecules being twisted at an angle across a thin layer of liquid crystal material. Here's a breakdown of the concepts involved: 1. **Liquid Crystals**: These materials have properties between those of liquids and solid crystals.