Light filter lets rays through from only one direction

Angle-sensitive device could improve photography and solar energy harvesting

By Andrew Grant, 11:06 AM March 28, 2014

Like a traffic cop directing cars, a layered stack of transparent materials permits light arriving from only a single direction to pass through. Such angle-sensitive filters could improve cameras and telescopes or allow solar cells to convert sunlight into energy more efficiently.

People have created effective light filters for thousands of years. Stained glass, for instance, filters light by color, allowing only a single shade to shine through while reflecting light at other wavelengths. But ...

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