The creation of a 'polarization ray trace' code is described using traditional lens design and analysis computer codes which assume that a ray represents a scalar plane wave and thin-film codes which implicitly use the vector nature of an incident plane wave. Calculations which explicitly use the vector formalism, to provide a more realistic model of light, must have the capabilities of an optical ray trace code and a thin-films code. Both codes exist as separate entities. An expedient method of obtaining a polarization ray trace capability is to merge both types of codes. A description of a method to merge the codes is presented by summarizing the calculations performed as a ray proceeds through an optical system. Polarization formalism is reviewed, and the problems and pitfalls associated with the merger of the two codes is presented.