Fabrication And Application For Liquid Crystal Fresnel Lens

As several3D films have drawn overwhelmingly high praise recently,developing3D display technologies has been considered as one of the mostimportant directions for display research. However, the visual fatigue isstill a thorny issue if watching3D image for a long time. Therefore, thedisplay is desired to be capable of switching between2D and3D modes.Several kinds of2D/3D switchable display technology have been proposed.Among them, the actively switched lenticular type with liquid crystal (LC)lens shows the most merits, which includes low crosstalk, hightransmittance, and possibility of using similar fabrication process ofconventional LC displays. However, the slow response rate is still themajor issue hindering the LC lens from being applied to consumerproducts. Thus Fresnel type LC lens is proposed to achieve the large lenspower and fast switching time with a small cell gap.There are several methods to get the Fresnel lens effect with LC lens.One is the multi-electrode LC Fresnel lens which makes discontinuousrefractive index distribution. But its refractive index distribution cannotreach the ideal Fresnel lens refractive index distribution due to the stronghorizontal electric field between two sub-lenses of the Fresnel lens.Another way of LC Fresnel lens fabrication is curing the LC/polymermatrix with a Gaussian-shaped laser beam which needs complicatedfabrication process and a photo mask. To make the ideal perfect refractiveindex distribution with simple fabrication and easy driving, a shiftingholographic technique to fabricate the LC/polymer Fresnel lens isproposed which can achieve one dimension Fresnel pattern by interferingtwo planar and spherical wave fronts with a shifting slit.Recently, polymer-stabilized blue phase liquid crystals (PS-BPLCs)within wide temperature range show potential for the LC photonicsapplication owing to their sub-millisecond response time, alignment-free process, and optically isotropic status when no voltage is applied. Also,several kinds of LC lens using BPLCs which offer polarizationindependency but small birefringence have been reported.To achieve effectively large birefringence, two kinds of Fresnel typeBPLC/polymer lenses by novel holographic fabrications are proposedwhich are named one-step-holographic-fabrication andthree-step-holographic-fabrication. One-step-holographic-fabrication isthat the polymer stabilization of BPLCs formed in Fresnel patterningprocess. Three-step-holographic-fabrication further introduces theprocesses of nematic LC washing-out and BPLC refilling. Compared withthe multi-electrode driving BPLC lens and the traditional fabricationmethod for Fresnel type LC lens, the Fresnel type BPLC/polymer lensescan be switched with a simpler driving, and its cost can be lowered byusing the holographic fabrications.