Shapeshifting Mobile Camera Lens Inspired by Human Eye
Picture taken at focus to infinity with the new lens.
By copying the human eye, scientists have developed what may be the world's smallest autofocus lens for mobile devices.
Apple, Nokia, Samsung and LG are among the companies already interested in the device because it promises to be faster and less power-hungry than conventional mobile device cameras, researchers say.
The majority of mobile phones today include built-in cameras, but these are not generally equipped with autofocus like the majority of standalone cameras. This is because autofocus requires these cameras to move their lenses back and forth until they correctly focus on an object, which can prove a slow and energy-draining process, and energy is a paramount concern for mobile devices.
Instead of focusing cameras by using motors to move lenses, researchers have now hit upon having cameras that focus just like the human eye by changing the shape of the lens. Human eyes squeeze or relax their flexible lenses to alter their curvature and thus how near or far they are focused.
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In order to mimic the human eye, scientists needed a soft lens, as well as materials that could mimic the eye muscles that control the lens. The resulting device was a complex sandwich of four different layers. The end product is just a half-millimeter thin and as little as 3.5 millimeters across.
At the very top is a ceramic film made of lead zirconia titanate, which acts much like the muscle in an eye. Under that is a thin glass membrane that serves as the flexible lens. Beneath this membrane is a synthetic transparent rubber, which acts like a cushion when the lens flexes. At the very bottom is a glass support.
The uppermost ceramic film is piezoelectric, meaning that it responds physically to electricity. When voltage is not running through it, the film remains flat, and light can pass through. However, when a voltage is passed through the film, it flexes, bending the underlying glass membrane into a lens shape that focuses light. The higher the voltage, the greater the curvature.
The resulting device is much faster than a motor-driven camera "because it's just changing shape you don't have to move chunks of mass around," said researcher Dag Wang, a microsystems engineer at SINTEF in Oslo, Norway, the largest independent research organization in Scandinavia. "It can perform a full autofocus cycle in 80 milliseconds, while you would need 500 milliseconds for a conventional system."
The new lens system also uses less than 1 percent of the energy to autofocus than a conventional motor-driven camera in a mobile device, Vang added. The sharpness of the resulting images is also comparable with other mobile device cameras.
After creating a working prototype, the researchers developed the lens further with the Norwegian optics firm PoLight. The company debuted a mobile phone camera with the new lens in February at the Mobile World Congress in Barcelona.
Mobile device manufacturers such as Apple, Nokia, Samsung and LG guide camera producers into what systems they might want, and all have expressed interest in the device, said Jon Herman Ulvensøen, vice president of advanced technology at PoLight.
"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," Ulvensøen said.
The issue the researchers face now is determining how to mass produce the device. "The components are mass-producible, but we still have to work on the integration steps," Wang said.
The researchers are also currently working on optical image stabilizer, macro and zoom systems based on this technology, Ulvensøen told InnovationNewsDaily, "all of which are also quite important for small cameras."