In a paper published in the journal Microsystems & Nanoengineering, the Stanford researchers presented a device that
Optical device - AGILE - is an invertedpyramid with a stub end. Light enters the square, tiled top at all angles and travels downwards, creating a brighter spot at the exit.
The principle of operation of the device is similar to a magnifyingglass. But in such lenses, the focus shifts when the source of radiation moves, and AGILE concentrates the sun's rays at one point, regardless of the angle at which the light fell.
Engineers used for their deviceglasses and polymers with different refractive index. The created lens is a material with a gradient index. Layers change the direction of light in steps rather than a smooth curve. In this case, the sides of the pyramids are mirrored, so any radiation going in the wrong direction is reflected back.
AGILE pyramid array. Source: Nina Vaidya, Stanford University
With the prototype device, the scientists were able to capture more than 90% of the light that hits the lens surface. At the output, light spots were formed that were three times brighter than the incoming light.
Solar panels work best when ondirect sunlight falls on them, the researchers explain. To collect as much energy as possible, many solar arrays rotate to follow the movement of the sun. This technology increases their efficiency, but makes production and use more costly. With the help of AGILE, such dynamic systems can be abandoned, the developers believe.
They also believe the new system will be useful for light control in solid-state lighting, laser connectors, and optical communications networks.
Cover image: Nina Vaidya, Stanford University
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