Lenses of Liquid

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Although this team is not the first to use liquid for lenses, they're the first to adjust the focal length by simply applying pressure. In 2004, Philips announced a liquid lens system, using a technique called "electrowetting," which relies on the intrinsic electrical conductivity of water-like liquids. With this technique, an electrical current is applied to a liquid lens, altering the bonds of the liquid's molecules, thereby changing the curvature of the drop. In January, the French company Varioptic introduced a cell phone containing an electrically variable liquid lens, which uses a version of electrowetting that, Rodriguez says, pre-dates the Philips design.

Stein Kuiper, the Philips researcher who developed the electrowetting technique for his company's liquid lenses, sees advantages in using pressure instead. "The electrical properties of the liquid are not relevant, which allows for a wider range of liquids, and thus optical and mechanical properties of the lens." Additionally, Kuiper says, the voltage required to change the pressure within a liquid lens system may be less than is required in a system using electrowetting. For these reasons, he says, Philips has "built up" intellectual property rights on both types of lenses.

Currently, Dharmatilleke and his team have partnered with a local company to fine tune and manufacture their liquid lens system, and they're seeking commercialization of the technology. As Rodriguez notes, applications for these lenses extend beyond camera phones, into webcams and portable medical devices.

Images courtesy of Isabel Rodriguez at the Institute of Materials Research and Engineering.