Liquid Crystal-Based Lenticular Lens Array with Laterally Shifting Capability of the Focusing Effect

Abstract

Recently, many approaches have been adopted to realize autostereoscopic three-dimensional (3D) displays that do not require glasses to be worn. Unlike other methods, including parallax barrier methods and integral imaging methods, lenticular lens array methods, with a lens array having parallel-arranged lenses of half-cylindrical shape, are used to provide a clear 3D image without diminished brightness. In previous studies, a variety of lenticular lens array methods with tunable focusing effects have been proposed as means of overcoming the intrinsic disadvantages of lenticular lens arrays. However, the existing lenticular lens array methods have only been focusing on the switchable viewing modes between the two-dimensional (2D) and 3D fields. There have thus far been approaches that demonstrate the tunable focusing effect of lenticular lens arrays using liquid crystal (LC), but the tunable range of the lenticular lens array methods has been restricted in the vertical or axial direction, incurring the bottleneck effect of laterally fixed viewing regions in lenticular lens array methods for autostereoscopic 3D displays. This thesis demonstrates a new type of LC-based lenticular lens array with the laterally shifting capability of focusing, consisting of two complementary lenticular lens arrays. Fabricated by the simple imprinting process, the proposed LC-based lenticular lens array exhibits a switchable focusing effect attributed to the index matching between the polymer lenticular lenses and the LC layer located between them. The refractive index of the bottom convex lens corresponds to that of the extraordinary axis of the LC, and the refractive index of the top concave lens is aligned in such a manner that the center of the top concave lens is located exactly above the boundary of the bottom convex lens, which is then matched with that of the ordinary axes of the LC. Therefore, for the input beam linearly polarized along the direction of the lenticular lens array, the focusing regions can be laterally shifted half the pitch of the lens according to the applied voltage. In order to be applicable for a new class of autostereoscopic 3D displays, the proposed lenticular lens array shows superb 3D viewing characteristics with laterally shifted viewing zones.