Eur. Phys. J. E 3, 159-163
Variable focal lens controlled by an external
voltage:
An application of electrowetting
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
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
