A Liquid Lens Driven by Bubble Actuator

We report an adaptive-focus lens using two immiscible liquids. The two liquids have a spherical interface and their border is confined by an iris diaphragm (ID). Using a bubble actuator to vary the aperture of the ID, the surface profile of the two liquid is changed, which in turn leads to a tunable focal length. In this paper, the liquid lens structure is depicted and the operation mechanism of the bubble actuator is introduced. For the liquid lens, the refractive index (n1) of the convex liquid is smaller than that of the concave (or surrounded) liquid (n2, n2-n1 ~ 0.2), so the lens is a diverging lens. As the aperture of the diaphragm is changed from ~ 5 to ~ 7.5 mm by the actuator, the focal length (f) of the lens could be tuned in the range of -168 mm ≤ f ≤ -55 mm. For the bubble actuator, it has the advantages of voltage control, large actuation pressure, reasonable speed, and low power consumption. Driven by the bubble actuator, our liquid lens can present a large aperture change, reasonable dynamic response, and precise focus control.

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