Nanocolloidal Lenses with Tunable Focal Length for an Augmented Reality System

A flat lens with a tunable focal length that does not require mechanical movement is highly desirable in augmented reality (AR) or virtual reality (VR) systems, but its development poses significant challenges. A colloidal lens that uses dielectrophoretic (DEP) manipulation of nanoparticle density in a colloid can be a good solution for achieving tunability in flat lenses. In this study, we investigated the optical properties of a nanocolloidal lens containing two-dimensional (2D) α-zirconium phosphate (α-ZrP) nanoparticles and optimized the lens design parameters to achieve low image distortion and large focal length tunability. We simulated the nanoparticle distribution function as a function of applied voltage for various lenses with different electrode designs, and the simulation results matched well with experimental observations. Additionally, we identified a condition for lower power consumption. Finally, we identified specific design parameters that allow for wide focal length control without image deformation and utilized them to fabricate lenses for a simple AR system. This study clearly demonstrates the potential of tunable nanocolloidal lenses, particularly in AR systems, by optimizing their design and performance.