Liquid Lenses Focus Without Moving Parts

March 3, 2005
While cell-phone cameras are growing in popularity, their electromechanical autofocus lens systems can be costly and complicated. Yet a liquid lens from Varioptic promises to lower these costs and complexities. Lacking any moving parts, this sin

While cell-phone cameras are growing in popularity, their electromechanical autofocus lens systems can be costly and complicated. Yet a liquid lens from Varioptic promises to lower these costs and complexities. Lacking any moving parts, this single-element lens is based on immiscible liquids. Small-diameter lens applications like cell-phone cameras will benefit from this simplicity.

Conventional focus technologies are based on the principle of moving lenses, i.e., precisely shifting delicate glass or plastic elements. The Varioptic approach uses two clear, immiscible liquids that have the same density. One liquid is conductive, while the other is not. The two liquids are sandwiched between panes of glass or plastic, depending on the application (see the figure).

The lens changes its focus through the physics of electrowetting. A current is applied to the conductive liquid, causing it to distend or flatten. This changes the shape of the border between the two liquids, focusing the lens.

Such a single-element lens system has a production cost that's considerably lower than the cost of comparable conventional autofocus lens systems. The lens can focus faster than electromechanical systems, and it consumes about one-tenth their power. Additionally, it requires just half the volume of a mechanical system.

A pair of liquid lenses and a conventional lens to correct for aberrations can form a combination autofocus and zoom lens with no moving parts. The company expects to release this lens for evaluation this year, and production is scheduled for 2006.

Variopticwww.varioptic.com
About the Author

Dave Bursky | Technologist

Dave Bursky, the founder of New Ideas in Communications, a publication website featuring the blog column Chipnastics – the Art and Science of Chip Design. He is also president of PRN Engineering, a technical writing and market consulting company. Prior to these organizations, he spent about a dozen years as a contributing editor to Chip Design magazine. Concurrent with Chip Design, he was also the technical editorial manager at Maxim Integrated Products, and prior to Maxim, Dave spent over 35 years working as an engineer for the U.S. Army Electronics Command and an editor with Electronic Design Magazine.

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