Optically isotropic switchable microlens arrays based on liquid crystal.

We present an optically isotropic switchable microlens array (MLA) based on liquid crystals (LCs) using the Joule heating electrode structure. The LC molecules were initially aligned vertically on the lens and electrode surfaces. By applying voltage to the transparent electrodes, the temperature of the LC layer could be changed. Above the clearing point temperature of LCs, the LC layer shows an averaged refractive index that differs from the nematic state refractive index. The MLA could have switching characteristics by index matching between the LC layer and polymer lens structure. The proposed switchable MLA shows high light efficiency with truly optically isotropic properties.