集会聚发散功能一体化的液晶柱透镜阵列

Liquid crystal lenticular lens array with switchable positive and negative power

本文提出了一种制备集会聚和发散功能一体化的液晶柱透镜阵列的方法。液晶柱透镜阵列呈“三明治”结构,从上到下依次为:上电极基板、液晶层、聚合物柱透镜阵列、下电极基板。为了将会聚和发散功能集成在单一液晶盒中,制备聚合物柱透镜阵列的紫外光敏胶的折射率(n_(p))需介于液晶的寻常光折射率(n_(o))和非寻常光折射率(n_(e))之间。通过在下基板表面修饰图案化疏水层,利用亲疏水效应使得紫外光敏胶自组装形成表面光滑、尺寸均一的柱透镜阵列。所制备的液晶柱透镜阵列有两种调节聚焦和散焦功能的方式:一种是改变入射光的偏振方向;另一种是施加电场调控液晶层的有效折射率。实验结果表明:当外加电压从0调节到0.7 V_(rms)时,液晶柱透镜的焦距从−4 mm调节到∞;当外加电压在1~7 V_(rms)变化时,液晶柱透镜阵列的焦距从6.0 mm调节到4.5 mm。该方法制备的液晶柱透镜阵列具有制备方法简单、器件结构紧凑、驱动电压低、调焦范围大等优点,在成像、显示、光通信等领域具有潜在的应用价值。

A method is proposed to prepare a liquid crystal lenticular lens array(LCLA)with switchable positive and negative focal length.The LCLA exhibits a“sandwich”structure which consists of top electrode substrate,LC layer,polymeric lenticular lens array,and bottom electrode substrate.In order to integrate the convergence and divergence functions in a single LC cell,the refractive index of the polymer should be between the ordinary refractive index(n_(o))and exordinary refractive index(n_(e))of LC material.The hydrophobic-hydrophilic strips array modified on the surface of the bottom substrate enables the formation of lenticular lens array self-assembly.There are two methods to switch the focal length of LCLA from negative to positive values:by changing the polarization direction of the incident light for 90°;or by applying an external electric field to adjust the effective refractive index of the LC layer.The experimental results show that when the applied voltage adjusted from 0 V_(rms) to 0.7 Vrms,the focal length of the LCLA changed from-4 mm to∞.When the applied voltage changed from 1 V_(rms) to 7 V_(rms),the focal length of the LCLA varied from 6.0 mm to 4.5 mm.The as-obtained LCLA has the advantages of simple fabrication,compact structure,low driving voltage and large range of focal length,which has potential applications in the fields of imaging,display,and optical communication.