| Microlenses are important components in modern miniaturized optical systems. Among these microlenses, emerging liquid-based variable-focus microlenses are of special importance, because they do not require complicated mechanical systems to adjust optical performance, and they are widely used in photonics, display and biomedical systems. Meanwhile, benefitting from rapid advancement of flexible electronics in recent years, microlenses made on flexible and curved substrates could have significant advantages over microlenses on flat substrates in enlarging the field of view, improving vision correction and creating three-dimensional (3D) effect.;Here, two types of variable-focus flexible microlenses are studied. One is actuated by thermo-responsive hydrogel and the other is controlled by electrowetting on dielectric (EWOD) mechanism. Their structures are both made of soft polymer. Therefore, they can be wrapped onto curved surfaces. The hydrogel-driven microlens has been fabricated into a structured lens array in which each lens can be actuated independently and they have the advantages of low cost and rapid fabrication process. Flexible electrowetting microlens, which has much faster response, has shown the potential to be integrated with a contact lens and it can also be expanded into a lens array with the help of a flexible electrode interconnection.;To facilitate lens design, a 3D surface profiling method has also been developed to measure the liquid-to-liquid interface in a liquid microlens using a Shack-Hartmann wavefront sensor. The obtained surface profile can be used to gain a better understanding of lens geometry and to estimate lens aberrations. |
