Liquid lens development

The lens, which has no moving parts, is capable of switching between two levels of magnification and is considered an important step on the development of liquid zoom lenses. It works by bending light using the curved boundary between watery and oily liquids, and focuses by the application of a voltage.

Potentially smaller and cheaper to build than conventional optics, Samsung have already begun using liquid lenses by building them into some cellphones.

"The creation of a liquid zoom lens would remove the need for mechanical parts, which would be a major advantage," says Peter Schreiber, a researcher at the Fraunhofer Institute for Applied Optics and Precision Engineering, Jena, Germany.

Changing a zoom lens’s magnification also affects its focus, and causes problems such as pincushion distortion and chromatic aberration. In order to preserve image quality across a range of magnification, zooms require 20 or more lenses, but so far, nobody has come up with a liquid lens design that can do that. A first step, however, is to design a lens that offers different levels of magnification rather than a continuous range.

Schreiber and colleagues Frank Wippermann and Andreas Bräuer worked with Varioptic, French pioneers of liquid lenses, to come up with a design that switches from a normal view to 2.5-times magnification. The design consists of four liquid lenses and three fixed plastic lenses and offers a magnification of 2.5 times, while when all four lenses are at their flattest there is no magnification.

“The complete length of the system from outer lens to image sensor is 29mm, but it should be possible to reduce that,” says Schreiber. Varioptic is now considering how to take the design on to the prototype stage.

“The lenses are arranged to prevent image distortion while minimising colour distortion. Red, green and blue images must be recorded in sequence and then combined digitally, a process that would increase exposure times,” says Schreiber, "finding less distorting liquids to build the lenses out of is the answer to that problem."