Scientists, led by an Indian-origin researcher, have developed a novel flexible sheet camera that can be wrapped around everyday objects to capture images that cannot be taken with conventional cameras. Led by Professor Shree K Nayar from Columbia University, researchers designed and fabricated a flexible lens array that adapts its optical properties when the sheet camera is bent.
This optical adaptation enables the sheet camera to produce high quality images over a wide range of sheet deformations. “Cameras today capture the world from essentially a single point in space,” said Nayar. “While the camera industry has made remarkable progress in shrinking the camera to a tiny device with ever increasing imaging quality, we are exploring a radically different approach to imaging,” he said.
“We believe there are numerous applications for cameras that are large in format but very thin and highly flexible,” he added. If such an imaging system could be manufactured cheaply, like a roll of plastic or fabric, it could be wrapped around all kinds of things, from street poles to furniture, cars, and even people’s clothing, to capture wide, seamless images with unusual fields of view.
The design could also lead to cameras the size of a credit card that a photographer could simply flex to control its field of view. The new “flex-cam” requires two technologies – a flexible detector array and a thin optical system that can project a high quality image on the array. One approach would be to attach a rigid lens with fixed focal length to each detector on the flexible array. In this case, however, bending the camera would result in “gaps” between the fields of views of adjacent lenses.
This would cause the captured image to have missing information, or appear “aliased.” To solve this problem, the researchers developed an adaptive lens array made of elastic material that enables the focal length of each lens in the sheet camera to vary with the local curvature of the sheet in a way that mitigates aliasing in the captured images.
This inherent optical adaptation of the lens is passive, avoiding the use of complex mechanical or electrical mechanisms to independently control each lens of the array. The researchers arrived at their passively adaptive lens array by optimising its geometry and material properties.
They fabricated their prototype lens array using silicone and demonstrated its ability to produce high image quality over a wide range of deformations of the sheet camera. “The adaptive lens array we have developed is an important step towards making the concept of flexible sheet cameras viable,” Nayar said.