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July 28, 2006

Transparent Fiber optic grid cameras

From MIT Technology Review: Light sensing optical fibers can make transparent cameras, uniforms that detect laser sightings, put onto screens for laser pointer control of the computer.



A system using these fibers could lead to transparent cameras that need no lenses.


The fibers are made of a semiconducting glass core, lined along its full length by wires that act as positive and negative electrodes, and surrounded by a transparent polymer. When light hits the photosensitive core, an electrical current in the fiber changes, registering the hit. A mesh of these fibers can then be used to identify the location of the light on a surface.For direction sensing, the researchers formed a grid of fibers into a sphere. A light beam from a flashlight first hits one side of the sphere and the grid registers the location. The light then passes through the sphere and out the other side, where it is detected again. Then an integrated circuit compares the entrance and exit points to calculate the path of the light.

The resolution of the images is limited by the need to space the fibers within the grid far enough apart that the first grid does not distort the image received by the second. The grids themselves also need to be separated, which could make the current system difficult to incorporate into some applications, such as on the skin of a car, where keeping the grids at a distance wouldn't be practical. But the researchers say work is currently being done that could overcome these limitations.

Nanomaterials and metamaterials could be applied to further enhance the capabilities after it is more refined.

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