Light detecting fibers may revolutionize the world of optics in medical applications because they overcome the limitations that current lens based systems have. Lenses are fragile, they are hard to make small enough to fit inside miniature endoscopes, and, in addition, they possess a host of intrinsic aberrations, such as astigmatism, spherical and chromatic aberration, coma, and other intrinsic problems. Now MIT researchers have demonstrated how a web of light sensitive coordinated fibers can be used to detect images, potentially opening way for a new industry to advance this technology and build real world products.
The new fibers, less than a millimeter in diameter, are composed of layers of light-detecting materials nested one within another.
Those layers include two rings of a semiconductor material that are light sensitive, each ring only 100 billionths of a meter across. Four metal electrodes contact each of the rings, extending along the length of the fiber, for a total of eight. Each semiconductor ring with its attached electrodes is in turn encased in rings of a polymer insulator that separate it from its neighbor.
The team starts with a macroscopic cylinder, or preform, of these elements. That preform is placed into a special furnace that melts the components, carefully drawing them into miniscule fibers that retain the original orientation of the various layers. The process can produce many meters of fiber.
Fink’s team demonstrated the power of their approach by placing an object – a smiley face – between a light source and a small swatch of fabric composed of the fibers that was in turn connected to an external amplifying electrical circuit and computer.
The individual fibers measure the intensity of the light illuminating them and convert it to an electrical signal. Importantly, they are also designed to differentiate between light at different wavelengths or colors. A mesh of fibers is then deployed to measure light intensity distribution at different wavelengths across a large area.
In the current work, the smiley face was illuminated with light at two separate wavelengths. This generated a distinct pattern on the fabric mesh that was then fed into a computer. From there, an algorithm described earlier by the Fink team in Nature Materials assimilates the data to create a black-and-white image of the object on a computer screen.
First author Fabien Sorin, a postdoctoral associate in RLE, DMSE and ISN, said that as the individual fibers become more sophisticated, it is possible to envision fabrics with more intriguing and complex functionalities, such as ones capable of producing crisper images in color.
Press release: A fabric with vision…