Camera phones will soon have lenses made from nothing more substantial that a couple of drops of oil and water, but will still be capable of auto focusing, and even zooming in on subjects.

So says Etienne Paillard, CEO of French start-up Varioptic.



The company was founded two years ago to exploit two core technology patents covering lenses based on the principles of electro-wetting. This is the tendency of liquid to spread on a substrate, Paillard explains. “It means we can tune the shape of the drop to create a lens. Think about a tunable lens, like in the human eye,” he suggests.



The lens has a simple structure: two liquids, of equal density, sandwiched between two windows in a conical vessel. One liquid is water, which is conductive. The other, oil, acts as a lid, allowing the engineers to work with a fixed volume of water, and provides a measure of stability for the optical axis. The interface between the oil and water will change shape depending on the voltage applied across the conical structure. At zero volts, the surface is flat, but at 40 volts, the surface of the oil is highly convex, Paillard said.




There are several obvious advantages to having a lens built like this. Because there are no moving parts, there is less to break and it should be more rugged. Power consumption is also very low: around a tenth of that of a motorised auto focus lens.



It also has the potential to be made very small. Paillard says that at the moment, the limit is a couple of millimetres, but that the company is researching ways of shrinking the lens further. Varioptics is now developing the lens for use in endoscopy as well as in camera phones. But the camera phone market is its priority right now.



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