Electroactive liquid lens driven by an annular membrane

Abstract

Unlike traditional focalization that recruits multiple moving lens elements to adjust focus, liquid lenses deliver adaptive focusing by simply tuning the surface profile of liquid or the elastomer that encloses liquid. Its simple and compact configuration, low cost, and actuation efficiency promise wide industrial, medical, and consumer applications. Dielectric elastomers (DEs), one type of commercially available soft active material, have been a good fit for creating adaptive optics. In this Letter, we present an adaptive, membrane-sealed liquid lens hydrostatically coupled to a concentric annular DE actuator. Electric actuation deforms the annular DE, which induces fluid transmission between the lens part and the actuation part for lens actuation. The maximum measured focal range was from 25.4 to 105.2 mm within 1.0 kV, which significantly outperforms the existing DE-actuated liquid lenses and eliminates the need for prestraining. The lens also enables varied focal ranges by simply adjusting its initial surface sagitta, providing flexibility for practical imaging applications.

Ultrafast All‐Polymer Electrically Tunable Silicone Lenses

“…As shown in Figure 2 reported on a lens in which an optical liquid is moved back and forth from the central lens to an annular DEA surrounding it and acting like a pump. [20] In that design, upon activation of the DEA, the curvature of a central membrane, which serves as the lens, decreases and could in principle reach a completely flat state and therefore an infinite focal length. A tuning range of 300% has been demonstrated for that geometry.…”

“…However, as the displaced fluid is forced through a channel, the fluidic impedance of this design slows down the overall response speed of the device: indeed, although the lens is also made with a silicone membrane, a response speed of a few hundred of miliseconds is reported. [20] So, the large tuning range comes at the cost of a slow response time.…”

Small, fast, and tough: Shrinking down integrated elastomer transducers

“…Upon activation of the DEA, the active membrane expands and the passive membrane relaxes, leading to a change of curvature of both membranes 9 . C) Similar concept than for B), but the actuator is located on the side, thus avoiding the need for transparent electrodes 56 .…”

“…It uses the same principle than of fluidically coupled membranes from the previous example, but instead of mounting the membranes back to back, they are positioned on the same plane, with the actuator having an annulus shape around the passive lens (figure 4 C) 56 . In theory, it should be possible to completely suppress the internal fluid pressure by activating the DEA, leading to a completely flat lens and to an infinite focal length.…”

Tunable Focus Liquid Lens with Radial-Patterned Electrode

“…Various mechanisms were demonstrated [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In contrast to other liquid lenses, a liquid lens based on the dielectrophoretic effect [8][9][10]18] is particularly attractive due to the advantages of easy fabrication, compact structure, direct voltage actuation, and low power consumption.…”