Examples using the most common waveplates follow.
A quarter-wave retarder is used to convert light between circular and linear polarization forms. It changes linearly polarized light to circularly polarized light, when the angle between the input polarization and the retarder fast axis, is 45 . When recombined, the exit light is circularly polarized. A quarter-wave retarder converts linearly polarized light to circularly polarized light, or vice versa. Similarly, this retarder orientation will convert input left-hand circular polarized light to vertical linearly polarized light for a reversed direction of travel.