An electromechanically driven dielectric elastomer based tunable reflector

Deformable optics offer numerous advantages over conventional optical assemblies, including compactness, cost-effectiveness, efficiency, and flexibility. This study focuses on a reflector based on dielectric elastomer actuators (DEAs) with an internal fluid (air) coupling. DEAs are a class of electroactive materials adept at accommodating substantial actuation strains and rapid responses. Fluid distributed between the active and passive parts remains entirely enclosed by the device and transmits actuation pneumatically. Dynamic maneuvers conducted through a series of controlled electrical signals demonstrate proper control over optical characteristics. However, DEs exhibit inherent flaws in dynamic actuation, referred to as instabilities, which are mitigated by applying an initial pre-stretch. The study identifies optimal parameters that confer stability to the reflector: minimum to no creep, zero residual vibrations, and low viscous losses. An analytical framework is developed to assess device performance, focusing on the spherical curvature assumption that closely resembles the behavior of tunable spherical reflectors. Additionally, an optical bench setup is employed to demonstrate the relationship between focal length and applied pressure. Notably, this paper underscores the potential of a DE-based variable focal length reflector to function effectively within a dynamic environment.