Electrically tunable soft solid lens inspired by reptile and bird accommodation

Abstract

Electrically tunable lenses are conceived as deformable adaptive optical components able to change focus without motor-controlled translations of stiff lenses. In order to achieve large tuning ranges, large deformations are needed. This requires new technologies for the actuation of highly stretchable lenses. This paper presents a configuration to obtain compact tunable lenses entirely made of soft solid matter (elastomers). This was achieved by combining the advantages of dielectric elastomer actuation (DEA) with a design inspired by the accommodation of reptiles and birds. An annular DEA was used to radially deform a central solid-body lens. Using an acrylic elastomer membrane, a silicone lens and a simple fabrication method, we assembled a tunable lens capable of focal length variations up to 55%, driven by an actuator four times larger than the lens. As compared to DEA-based liquid lenses, the novel architecture halves the required driving voltages, simplifies the fabrication process and allows for a higher versatility in design. These new lenses might find application in systems requiring large variations of focus with low power consumption, silent operation, low weight, shock tolerance, minimized axial encumbrance and minimized changes of performance against vibrations and variations in temperature.

Smart Lenses with Electrically Tuneable Astigmatism

“…Using silicone membranes to actuate those structures has led to the world-fastest tuneable lenses made of smart materials, capable of response times down to ∼175 μs 14 . Moreover, that tuneable lens concept has also been demonstrated in a fully elastomeric (solid) version 30 .…”

Electrically Tunable Lenses: A Review

“…It consists of a planoconvex PDMS lens arranged on the inner circular region of an annular DE actuator; upon electrical activation, the actuator radially squeezes the lens, which therefore bulges, reducing its focal length. This concept was first described by Pieroni et al (2016), who created (by mold casting) a customizable PDMS lens directly on the DE membrane; a 12 mm-aperture lens showed a focal length change from 36.6 to 16.6 mm at 3.7 kV. This design was modified by Nam et al (2018), to implement a stretching (instead of compression) of the lens, by arranging it on a parallel plane and connecting it to the actuation membrane via plastic (Choi et al, 2009); (B) schematic of a lens pulled by radial extenders; (B9) servo-motors-actuated prototype sample, reproduced with permission from (Liebetraut et al, 2013); (C) schematic of a lens operated by an electrostatic actuator, consisting of stiff annular electrodes that squeeze a soft membrane; (C9) array of prototype samples, reproduced with permission from (Wang et al, 2017); (D) schematic of a lens operated by piezoelectric bending actuators, which deform a thin glass membrane acting on the lens; (D9) commercial product by poLight, adapted from (Polight, 2021); (E) schematic of a lens operated by a transparent DE actuator, which forms the whole lens and increases its own curvature by buckling (note: unidirectional buckling should be facilitated by an initial asymmetry); (E9) prototype sample, reproduced with permission from (Son et al, 2012).…”

Bioinspired Artificial Eyes: Optic Components, Digital Cameras, and Visual Prostheses

“…Recently introduced liquid‐based lenses with the support of electric fields also facilitate the reduction in longitudinal spherical aberrations by easily shaping aspherical lenses (Figure f), which is a challenging task in rigid optics. Other physical actuation methods include electrically shape‐tunable lens systems and mechanics‐based accommodation …”