Photo credit: Nina Vaidya
Stanford University researchers, led by engineering researcher Nina Vaidya, have developed an optical concentrator that can be used to gather and concentrate light, regardless of the angle or frequency of that light. Called AGILE (Axially Graded Index Lens), it resembles an upside-down pyramid with the point lopped off, allowing light to enter the square, while the tile-able top funnels it downwards to create a brighter spot at the output.
Early prototypes managed to capture 90% of the light that hit the surface and created spots at the output that were three times brighter than the incoming light. When AGILE is installed in a layer on top of solar cells, they could make solar arrays far more efficient by capturing not only direct sunlight, but also diffusing light that has been scattered by the Earth’s atmosphere, weather, and seasons. Who knows? It may even work on the International Space Station’s solar array.
It’s a completely passive system – it doesn’t need energy to track the source or have any moving parts. Without optical focus that moves positions or need for tracking systems, concentrating light becomes much simpler. We wanted to create something that takes in light and concentrates it at the same position, even as the source changes direction. We don’t want to have to keep moving our detector or solar cell or moving the system to face the source,” said Vaidya, who is now an assistant professor at the University of Southampton, UK.
