''... researchers at Rensselaer Polytechnic Institute, in Troy, NY, are proposing a type of liquid lens--made of only two drops of water--that changes shape when bombarded with sound waves.
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Extremely small cameras and many cell phones simply don't have enough room to allow users to move a rigid lens the distance required for a range of focal lengths.
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The researchers' lens system, described in October's Nature Photonics, is composed of a Teflon cylinder less than two millimeters in diameter. The cylinder is overfilled with water so that droplets bulge out on either side. A speaker is hooked up to one side of the cylinder, which is in a pressure-sensitive chamber. The researchers pumped sound at between 50 and 160 hertz into the chamber, changing the shape of the droplet's surface.
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