Researchers at Columbia University are working to produce a flexible sheet camera with stretchable lenses. The program aims to create very thin, high resolution cameras that can be wrapped around surfaces like car panels. Currently in concept form, the sheet lens array that such a camera might use has been developed to produce a seamless image on a flexible sensor when it is bent or wrapped around a physical object.

The focus of the research is in creating flexible lenses that are capable of changing shape (and hence the effective focal length) as they are stretched and compressed so that the imaging sensor can record a detailed image whatever the field of view.

With fixed lenses, gaps appear between the coverage of the lenses as the substrate is bent (left), but in the researcher’s flexible lens example (right) the lenses bend with the substrate and offer continuous coverage of the subject.

In previous attempts at flexible lens arrays only the substrate has been flexible, and as the sheet of lenses has been bent gaps have appeared in the subject coverage as the angle between the lenses increased beyond their individual field of view. These gaps lead to aliasing artifacts in the final image that can’t be corrected in post-processing software. In this new concept the lenses are also flexible and they stretch as the sheet bends, altering their focal length and providing better sampling of the subject.

So far the research has successfully produced a sheet of silicone with lenses molded on one side and a diffuser behind a sheet of apertures on the other. The apertures act as a low pass filter ensuring light from each molded lens reaches only one point on the viewing diffuser.

Images created with the substrate bend by different degrees, showing how the field of view changes

The system hasn’t actually been used with a sensor yet, but the study did use it to project images on to the diffuser screen to determine how effective it would be. Bending the sheet increased and decreased its field of view, or effective focal length, and the images were displayed without missing areas. All that is required now is a flexible sensor to go with it.

An array of lenses was formed by pouring silicone into a metal mold

The intention of the project is to work towards finding a way of making sheets of lenses to work with photosensitive materials that will record images when wrapped around real-world objects. The researchers want ultimately be able to produce these sheet cameras in roll format at a low cost so that the sheets can be cut to size to suit specific uses.

The released information suggests a sheet camera could be wrapped around the panels of a car to give the driver a view from all angles. Alternatively sheet cameras could be used by consumers to take normal pictures but with the user bending the sheet to alter the field of view, or zoom effect, of the system.

For more information see the project’s page on the University of Columbia website.

Press release:

Articles: Digital Photography Review (dpreview.com)