A new imaging system developed at the MIT Media Lab uses an open-ended bundle of optical fibers — no lenses, protective housing needed.
The fibers are connected to an array of photosensors at one end; the other ends can be left to wave free, so they could pass individually through micrometer-scale gaps in a porous membrane, to image whatever is on the other side.
Bundles of the fibers could be fed through pipes and immersed in fluids, to image oil fields, aquifers, or plumbing, without risking damage to watertight housings. And tight bundles of the fibers could yield endoscopes with narrower diameters, since they would require no additional electronics.
The positions of the fibers’ free ends don’t need to correspond to the positions of the photodetectors in the array. By measuring the differing times at which short bursts of light reach the photodetectors — a technique known as “time of flight” — the device can determine the fibers’ relative locations.
In a commercial version of the device, the calibrating bursts of light would be delivered by the fibers themselves, but in experiments with their prototype system, the researchers used external lasers.
“Time of flight, which is a technique that is broadly used in our group, has never been used to do such things,” says Barmak Heshmat, a postdoc in the Camera Culture group at the Media Lab, who led the new work. “Previous works have used time of flight to extract depth information. But in this work, I was proposing to use time of flight to enable a new interface for imaging.”
The researchers reported their results today in Nature Scientific Reports. Heshmat is first author on the paper, and he’s joined by associate professor of media arts and sciences Ramesh Raskar, who leads the Media Lab’s Camera Culture group, and by Ik Hyun Lee, a fellow postdoc.