An electrically tunable polarization and polarization-independent liquid-crystal microlens array for imaging applications

Abstract

In this study, a polarization-independent microlens array composed of two layered nematic liquid crystal (LC) materials with orthogonal alignment and separated by a double-sided indium-tin oxide silica with a thickness of ∼500 μm, is proposed. The functioned stacking of two polarization LC microstructures lead to an electrically tuning polarization and also polarization-independent light control architecture. Experimental investigations reveal key characters such as a high beam utilization efficiency of more than 90% and a compound point spread function tuned electrically. Dual-mode imaging including the polarization mode and the polarization-independent mode can be realized based on the novel configuration with both independent voltage signals applied over two functioned LC layers. The normalized focusing intensity demonstrates a special property of no polarization dependence on beams processed. An image criteria for evaluating the quality of polarization-insensitive images based on the difference image between the horizontal and vertical polarization images, is introduced. Considering the advantages of electrically tunable composed focal length and then switching the polarization and polarization-independent mode, it can be expected that the developed devices can not only be used to measure and further tune the polarization state of beams propagating in LC layers but also acquire high quality target images.