Double Refraction

Double Refraction: refraction which occurs whenever a light ray propagates within an anisotropic optical medium (substances that crystallize in the Hexagonal, Trigonal and Tetragonal Crystallographic Systems of the Dimetric Group, and in the Monoclinic and Triclinic Crystallographic Systems of the Trimetric Group) resulting in the splitting of such a ray in two components travelling in two different crystallographic directions and therefore at two different speeds.

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