Ray tracing programs generally treat rays as purely geometric entities, which have only a position, orientation, and phase. For example, a ray is completely described at a surface by the ray intercept coordinates, the direction cosines which define the angles the ray makes with respect to the local coordinate axes, and the phase, which determines the optical path length or difference along the ray.
 
At the boundary between two media, such as glass and air, refraction occurs according to Snell's law. Usually, the effects at the interface which do not affect beam direction are ignored. These effects include amplitude and phase variations of the electric field which depend upon the angle of incidence, the incident polarization, and the properties of the two media and any optical coatings at the interface.

Polarization analysis is an extension to conventional ray tracing which considers the effects that optical coatings and reflection and absorption losses have on the propagation of light through an optical system.

ZEMAX has detailed analysis capabilities for almost any coating or birefringent medium. However, it is sometimes required to use simpler models, because of a lack of data of the real prescription data. For example, ZEMAX supports IDEAL and TABLE coatings for use when real coating data is not available. In a similar manner, the Jones matrix can be used to describe polarization components such as polarizers and retarders without doing detailed physical modeling. The Jones matrix is a useful 'black box' approach to modeling some polarization effects.