L2

Geometrical optics a branch of optics where light is described by rays. Light rays are conceived as geometrical lines originating from sources, extending through media, and being revealed by detectors; their directions account for paths along which light flows.

Light paths are intrinsically related to the refractive index n of the media, where light propagates (n is the ratio between the speed of light in vacuum and in the medium).

However Physical Optics refers to a powerful electromagnetic simulation method used in the study of real optical systems. It involves considering diffractions and reflections between optical elements to predict the behavior of light.