Abstract: A stress-induced polarization converter in the form of a zero power optical window or, alternatively, a single element, positive or negative power optical lens, that is subject to a controlled amount of symmetric, peripheral stress. The stress may be provided by appropriate mechanical, thermal, hydraulic, electromagnetic/piezo, annealing/molding, or other known techniques and may be trigonal or four-fold. Axial foci can be created by applying the controlled, symmetric, peripheral stress. The separation distance between the foci can be controlled by controlling the magnitude of the applied symmetric, peripheral stress.

Abstract: A stress-induced polarization converter in the form of a zero power optical window or, alternatively, a single element, positive or negative power optical lens, that is subject to a controlled amount of symmetric, peripheral stress. The stress may be provided by appropriate mechanical, thermal, hydraulic, electromagnetic/piezo, annealing/molding, or other known techniques. The applied symmetric stress will advantageously be trigonal or four-fold, but is not so limited. Advantageously, the polarization converter will be exhibit greater than about one wave of retardation and, in a particular advantageous aspect, will exhibit at least two waves of phase retardation. The stressed lens or window will be characterized by a smoothly varying birefringence that, near center, will exhibit substantially circular contours of equal birefringence. When illuminated by circularly polarized light, the polarization converter will produce concentric rings of alternating right and left circular polarization.