In this article, the Register writes that "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." The lenses, developed by the French company Varioptic, contain drops of oil and water, acting respectively as conductor and insulator, and sandwiched between two windows. These liquid lenses could replace glass or plastic ones because of several advantages: no moving parts, leading to better reliability; a very small power consumption; very small dimensions (diameter: 8mm; thickness: 2mm); and a very fast response time of 2/100th of a second. You can expect the first camera phones using these liquid lenses as early as Christmas 2005. These lenses might also appear in medical equipment, such as endoscopes, optical networking equipment or surveillance devices. Read more.
The company was founded two years ago to exploit two core technology patents covering lenses based on the principles of electrowetting. This is the tendency of liquid to spread on a substrate, explains Etienne Paillard, the CEO of the company. "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.
"The liquid lenses that we develop are based on the electrowetting phenomenon described below: a water drop is deposited on a substrate made of metal, covered by a thin insulating layer. The voltage applied to the substrate modifies the contact angle of the liquid drop. The liquid lens uses two isodensity liquids, one is an insulator while the other is a conductor. The variation of voltage leads to a change of curvature of the liquid-liquid interface, which in turn leads to a change of the focal length of the lens." (Credit: Varioptic).
What are the advantages of these liquid lenses?
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.
Don’t forget the Dance Halls
Warwick and Savoy,
Where he picked his women, where
He drank his liquid joy.
—Gwendolyn Brooks (b. 1917)
And when will we see the first camera phones equipped with these lenses?
The company has a non-exclusive licensing deal with a subsidiary of Samsung to develop the lenses for use in its camera phones. Paillard expects products will be on the shelves by Q1 2006 at the latest, and maybe even in time for Christmas next year.
The first product will be the auto focussing lens, but in another year's time Varioptics will have a true zoom capability, using two of the liquid lenses, Paillard says. "We've just proven in simulation that a 3x zoom is possible. We're building the prototype now."
Varioptic has filed two patents to protect its technologies. Here are the direct links to a lens with variable focus and a method for centering a drop of liquid on a given point on a surface.
If for a reason or another, these links appeared to be broken, please go to the Intellectual Property Digital Library which provides access to intellectual property data collections hosted by the World Intellectual Property Organization (WIPO). Then choose the patents database and enter the numbers of the patents in the search box. These numbers are respectively 99/18456 and 00/58763.
It's worth noting that the Register published in March 2004 a story named "The $5 'no moving parts’ fluid zoom lens -- twice" in which it compared the Varioptic patents with another one filed by Philips. As the Philips patent clearly made references to the Varioptic ones, it is highly possible that Philips needs to license the Varioptic technology if it wants to use it.
Sources: Lucy Sherriff, The Register, December 1, 2004; John Lettice, The Register, March 5, 2004; and various websites
Related stories can be found in the following categories.
Handhelds
Optics
Patents
Photography.