Flexible sheet camera bends to give a new field of view
Researchers have developed a sheet camera with a flexible lens array which could be wrapped around everyday objects, turning them into cameras. The project, which uses elastic optics, could also see the development of credit card-thin cameras which a photographer simply bends to change the field of view.
While we've previously seen researchers miniaturizing cameras and lenses so they can be used in new situations, the team from Columbia University has taken a different approach. Led by Shree K. Nayar, T.C. Chang Professor of Computer Science at Columbia Engineering, it looked at producing a sheet camera which would enable any surface to capture visual information.
Using traditional fixed focal length lenses in such a lens array would mean that as the array sheet is bent, gaps are formed between the lenses' fields of view, meaning information is missing. As such, the researchers set about designing a flexible lens array which also adapts its optical properties when the sheet camera is bent.
By using an elastic material for the lenses, the team was able to design an array where the effective focal length of each lens varies with curvature. As it is bent, the field of view increases. The result is an adaptive lens array that can produce quality images over a wide range of sheet deformations.
To prototype this, the researchers fabricated a lens array using silicone in a 33 by 33 lens array mold machined from aluminum. An aperture sheet made of nylon was then glued to the bottom of the lens array, and a diffuser attached. A Nikon D90 camera was then placed under the array and used to photograph the 33 by 33 spots it created on the diffuser as it was bent in a vise.
The tests found the field of view of the array increased with curvature, taking in more of the view as the array was bent, but that the resulting image remained free of aliasing artifacts. The prototype array was used used to capture up to a 52 degree field of view as it was bent.
Given the early stage of the research we shouldn't expect to see sheet cameras any time soon, and the team says the next step will be to develop large-format detector arrays to go with the deformable lens array. However, it does pave the way for cameras which could be wrapped around everyday objects such as cars or lampposts, or even give you a flexible camera you can slip in your wallet.
The project "Flexible Sheet Cameras With Elastic Optics" is to be presented at the International Conference on Computational Photography at Northwestern University in Evanston, Illinois, which runs from May 13 to 15.
You can watch a video presenting the research below.