The division of light into two components (an "ordinary" and an "extraordinary ray" ), found in materials which have two different indices of refraction in different directions (i.e., when light entering certain transparent materials, such as calcite, Eric Weisstein's World of Chemistry splits into two beams which travel at different speeds). Birefringence is also known as double refraction.
The quantity known as birefringence is defined as
Crystals possessing birefringence include hexagonal (such as calcite), tetragonal, and trigonal crystal classes exhibit birefringence, and are known as uniaxial. Orthorhombic, monoclinic, triclinic exhibit three indices of refraction. They are therefore trirefringent and are known as biaxial. Birefringent prisms include the Nicol prism, Glan-Foucault prism, Glan-Thompson prism, and Wollaston prism.
Index of Refraction, Kerr Cell, Kerr Effect, Mechanical Birefringence, Nicol Prism, Optical Sign, Photoelastic Effect, Photoelasticity, Refraction, Stress Refringence
