Philips Debuts Revolutionary Fluid Focus Lens

by Tony Fonseca
Published on Mar 8, 2004 12:00 AM



Philips this week announced the debut of a new lens that utilizes fluid to change focal length without mechanical lens elements. The unique aspect of this lens is that it contains no moving parts and thus is a great candidate to be used in small devices where size is a factor such as digital cameras, cell phones, endoscopes, home security systems, and optical storage drives.

Philips is saying that the technology will be especially useful for cell phone cameras, where an extremely small lens has to be packed into a very small devise. With the current trend in consumer camcorders for smaller and smaller products, these lenses may one day have applications in the consumer camcorder industry.

According to the press release the new lens works by combining two immiscible (non-mixing) fluids of different optical properties into a device for focusing light. One of the fluids is an electrically conductive aqueous solution and the other is a non-conducting oil solution. Both of these fluids are contained in short tube with transparent end caps. The internal surface of the tube is coated with a water repellent coating that causes the solution to congeal into a hemispherical mass at the end of the tube where it acts as a spherically curved lens.

The actual shape of the lens is adjusted by the application of an electric field across the hydrophobic (water repellent) coating such that it becomes less water-repellent. This process is known as electro-wetting and although different from the physical act of focusing the human eye, it mimics the effect by seamlessly warping the focal surface.

The lens is very durable and can change focal length very rapidly from 5cm to infinity in less than 10 ms. Previously some larger special effects lenses have made use of fluid dynamics to warp and focus an image, but this is the first time that this sort of technology has been applied to such a small form factor.