Light-Detecting Sphere

MIT researchers led by Yoel Fink have developed an optical system made of webs of light-detecting fibers. The meshes are currently able to measure the light direction, intensity, and phase. The investigators expect that in time the system will be capable of much more, with potential applications ranging from improved space telescopes to clothing that provides situational awareness to soldiers or even the visually impaired.

The fibers, ~1 mm dia., consist of a photoconductive glass core with metal electrodes running along the core's length. The structure is enclosed in a transparent polymer insulator. The spherical configuration allows a web to sense the entire volume of space surrounding it. The sphere can also detect the direction of incoming light by observing its entrance and exit points. Entering light produces a change in current in an external electrical circuit.

The team has also placed two 2D webs in parallel, which can generate rough images of objects placed near them and lit from behind. The images appear on a computer screen as a reconstruction of the distribution of light intensity.

In addition to Fink, the team consisted of John Joannopoulos, Ayman Abouraddy, Mehmet Bayindir, Ofer Shapira, Fabien Sorin, Jerimy Arnold, Dursen Hinczewski, and Yigal Migdal. The work is being funded by the MIT Institute for Soldier Nanotechnologies, the DOE, DARPA, and the NSF.(