American researchers have developed a novel sheet camera that can be wrapped around everyday objects to capture images that cannot be taken with one or more conventional cameras.
The team from the School of Engineering at Columbia University in New York 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.
Team leader Professor Shree Nayar said cameras today capture the world from essentially a single point in space.
“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 said 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. This 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, 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.
To solve this problem, the Columbia team 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. This passive optical adaptation of the lens avoids 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.
Nayar said the next step will be to develop large-format detector arrays to go with the deformable lens array.
The lens array developed at Columbia Engineering. Photo: Columbia Computer Vision Laboratory