title: Halfwave retarder for all polarization states.
abstract: We show that a device consisting of an optical rotator placed between two identically oriented quarter-wave plates always acts as a halfwave retarder for some pair of orthogonal elliptically polarized states that can be selected by linear adjustment of the optical rotation and orientation of the quarter-wave plates.
authors.forename: R
authors.initials: R
authors.lastname: Bhandari