2018 Impact factor 1.686
Soft Matter and Biological Physics

Eur. Phys. J. E 3, 159-163

Variable focal lens controlled by an external voltage:
An application of electrowetting

B. Berge - J. Peseux

Laboratoire de Spectrométrie Physique (UMR Université Joseph Fourier-CNRS, 5588) B.P. 87, 38402 St Martin d'Hères, France
bruno.berge@ens-lyon.fr

Received 1 December 1999

Abstract
We use electrocapillarity in order to change the contact angle of a transparent drop, thus realizing a lens of variable focal length (B. Berge, J. Peseux, Patent deposited in Grenoble France, October 8th 1997, numéro d'enregistrement national 97 12781). The key point is the application of gradients of wettability, which control the shape of the drop edge, in our case a centered circle of variable radius. The quality and reversibility of the lens are surprisingly good. The optical power variation can be 5 to 10 times the one of the human eye, for a comparable diameter, with a typical response time of 0.03 s and a dissipated power of a few mW.

PACS
68.45.Gd Wetting - 42.15.Eq Optical system design - 68.10.-m Fluid surfaces and fluid-fluid interfaces

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