Optic axis of a crystal (source code)

= Optic axis of a crystal
{wiki=Optic_axis_of_a_crystal}

The optic axis of a crystal is a specific direction within the crystal where light behaves in a particular way. In uniaxial crystals (like quartz or calcite), there is a single optic axis along which light travels without splitting into two rays; this direction is known as the optic axis. For light traveling along the optic axis, it exhibits isotropic behavior, meaning that the refractive index is the same in all directions.