Depth-extended integral imaging system based on a birefringence lens array providing polarization switchable focal lengths

Abstract

An integral imaging system enabling extended depth of field was proposed and demonstrated based on a birefringence lens array (BLA) whose focal length was switched via the light polarization. The lens array system was constructed by combining two different liquid crystal(LC) embedded lens arrays, BLA I and II, which were fabricated by injecting a ZLI-4119 LC and an E-7 LC in between a lens array substrate and an ITO (indium-tin-oxide) glass plate respectively. The BLA I played a role as a convex lens only for the polarization parallel to the ordinary axis of the corresponding LC, but it serves as a plain medium for that along its extraordinary one since the refractive indexes of the lens and the LC are almost identical. Meanwhile, the BLA II played a role as a concave lens only for the polarization parallel to the extraordinary axis of the LC but as a plain medium for that along its ordinary one. As a result, the focal length could be switched via the polarization, and it was measured to be 680 mm and -29 mm. For the proposed system with the prepared BLAs, both real and virtual three-dimensional (3D) images were efficiently reconstructed at the positions of z=1300 mm and z=-30 mm with no significant degradation in the resolution, indicating its depth of field range.