The world’s smallest autofocus lens
The world’s smallest autofocus lens for mobile devices is ready, and Apple and Nokia are among the companies interested in introducing it. Christina Benjaminsen wrote this story for Gemini.
Six years ago a group of research scientist for SINTEF, Scandinavia’s largest research organization, working at MiNaLab in Oslo began throwing around ideas for new energy-saving features which would provide autofocus in small optical systems.
Most mobile telephones today have built-in cameras, but these are not equipped with autofocus like ordinary photographic cameras. The small aperture results in a acceptable depth of focus, but also admits limited amounts of light, making indoor photography difficult and the photos are often not sharp.
An important requirement for the researchers was the ability to focus the lens sharply. This is normally achieved by moving lenses, but this requires energy, and the optimal solution would therefore be to change the curvature of the lens itself, just like the lens of the human eye.
world’s smallest autofocus lens
What the researchers needed was therefore some sort of soft and variable lens and a material which could mimic the muscles of the eye which control the lens. Research scientist Dag Vang recalled:
The idea of creating an autofocus lens using the principles found in nature got us thinking at the time. The result was a sketch of an optical “sandwich” consisting of extremely thin glass plates, a polymer, a gel material and a metal alloy with flexible properties – all at very small scale.
The required material was developed to order. To succeed, the researchers needed to make a ring of material contract and expand almost without expending energy – and at the same time construct a gel-based lens in the middle.
After a year of intense development work the research team had a working prototype, and in 2006 they signed a project contract with the Norwegian company PoLight in Horten. This small company had been working on optical systems for some time and saw the potential for introducing the technology to the mobile phone market.
Earlier this year the company demonstrated the new camera lens, integrated into a mobile phone camera, to interested specialists at the world’s largest mobile device exhibition, Mobile World Congress in Barcelona. Jon Ulvenson, Managing Director of PoLight, said:
There was great interest because of the picture quality provided by the lens. We are now in discussions with several of the major mobile phone manufacturers and subcontractors, and I hope we will have a contract by the end of this year.
Christina Benjaminsen has been a regular contributor to the science magazine Gemini for 11 years. She was educated at Volda University College and the Norwegian University of Science and Technology, where she studied media and journalism.
Bottom line: To save energy, researchers have designed the world’s smallest autofocus lens. It’s curved, much like the lens of the human eye.