Light consists of electric and magnetic fields, and the direction of the electric field is the direction of polarization. Light polarization can be linear, elliptical, or random. Polarizers are optical components that only pass one polarization direction. Retarders, or wave plates, utilize birefringence properties of materials to alter the polarization state of an incident light. When light passes through a retarder, one polarization component is phase delayed relative to the other, and therefore the polarization state is altered. A method of calculating polarization states is to use W. B. Jones vectors and matrices, where incident and transmitted polarization states are given by vectors, and the transformation matrix representing polarization component is given by a matrix. The incident light makes the molecule oscillate in the direction of the incident light polarization. When the incident light is randomly polarized, namely, it contains polarization components both in x- and y-directions, then scattered light propagating in y-direction is polarized in x-direction.