Optical axisof crystal

Optical axisbirefringence

The optical axis is an imaginary line that defines the path along which light travels through an optical system, such as a lens or crystal. It serves as a reference line for understanding how light interacts with various materials, especially in contexts where birefringence and optical activity affect light propagation. This concept is crucial for analyzing how different optical phenomena can alter the behavior of light in non-uniform materials.

Optical Activity: The ability of certain materials to rotate the plane of polarization of light as it passes through them.

Birefringence: The optical property of a material where it has a different refractive index depending on the polarization and direction of light passing through it.