Liquid Lens – thinner and cost effective
Posted by evolvingwheel on July 28, 2007
A German research team at the Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, Germany, has come up with a liquid lens that has no mechanical moving parts and can switch between two levels of magnification in a flick of a switch. The most amazing part of the development is the size and weight advantage of the device. The lens works on the principle of bending of light between multiple liquid layers of varying densities. The boundaries between these liquid boundaries are manipulated by applying a small voltage across them. Light is then made to focus by making it pass through those controlled boundaries.
One big application that the researchers are betting on is in the zoom lenses. Commercial zoom lenses are heavy, large, and expensive with innumerable lenses packed together. Liquid lenses can provide a new alternative with no moving parts. The size advantage is incredible too. However, the biggest hurdle is to create a whole range of magnification rather than two specific magnifications. The researchers are working on finding the right kind of liquids that can provide the altering zooms across a wide range.
Samsung is already using liquid lenses in its cell phone cameras. Currently, these lenses are finding more use in small digital photographic devices. However, if this lens theory is physically implemented in mainstream photography, the cost benefit and commercial profitability looks very lucrative.
Read more below.
A fluid-filled lens that changes focus in response to an electrical current could provide cheaper optical systems for electronic gadgets like camera phones and DVD players.
Conventional optical systems change focus by altering the distance between two solid lenses, requiring moving parts. In contrast, the FluidFocus lens developed by Philips manipulates two fluids using current to bring objects into clearer view.
The new lens comprises of a short cylinder filled with two liquids – an electrically conducting aqueous solution and a non-conducting oil. The fluids are immiscible, forming two distinct layers, and also refract light differently.
The walls of the cylinder is coated with a material that repels the aqueous solution but not the oil. This causes the interface of the two liquids to form a curve towards the centre of the lens.
When an electrical current is applied, the walls of cylinder becomes less water repellent. This process – called electrowetting – changes the distribution of the two fluids in the lens and causes the curve to flatten out, changing its focal length. The current can even reverse the curvature of the lens from convex to concave.
In principle, two lenses of this type could be used together to create an optical system that is also capable of zooming in and out.
Stein Kuiper, at the Philips research laboratory in Eindhoven, Netherlands, says the simplicity of the design promises to lower manufacturing costs. “It’s a very simple concept and we think it will be very cheap,” he told New Scientist.
But, because the technique relies on the surface tension of the liquids inside the lens, it cannot be used to make lenses larger than a centimetre in diameter. This would place a limit on the resolution of images.
Nonetheless, Kuiper believes that FluidFocus lenses could be especially useful for reading from Blu-Ray DVD disks, which store information more densely than ordinary DVDs. Blu-Ray players require highly accurate optical systems capable of adjusting for distortions that naturally occur during dual layer disc reading and writing.
The FluidFocus lens will be demonstrated at the technology fair CeBit, in Hannover, Germany, next week. Kuiper says the first devices that incorporate fluid lenses be available by 2005.
Picture: Courtesy NewScientist