Abstract: A Faraday rotator comprising an optical element having an optical axis, a means for generating a magnetic field along the optical axis of the optical element in order to rotate a plane of polarization of polarized light about the optical axis, and a means for moving said optical element such that varying portions of the optical element can be enclosed over or withdrawn from the means for generating a magnetic field. In a preferred embodiment the optical element is held within a clamp contained within a movable screw which can be turned so as to vary the amount of the optical element surrounded by the means for generating the magnetic field.