An optical element includes a support plate composed of optically active material having an optic axis and at least two planar-parallel portions supported by the support plate, each of the at least two planar-parallel portions composed of optically active material having an optic axis. When a first linearly polarized light ray passes through a first section of the optical element along a direction parallel to the optic axes, a plane of oscillation of the first linearly polarized light ray is rotated by a first angle and when a second linearly polarized light ray passes through a second section of the optical element along a direction parallel to the optic axes, a plane of oscillation of the second linearly polarized light ray is rotated by a second angle different from the first angle.