Science News looks at the world through the eyes of Dalmanitina socialis, a creature extinct for 400 million years who could focus on objects as close as 3 centimeters and as far as 2 kilometers at the same time thanks to an eye with a very strange internal structure:
“In optics, there was a problem,” says Amit Agrawal, a physicist at the National Institute of Standards and Technology in Gaithersburg, Md. If you wanted to focus a single lens to two different points, you just simply could not do it, he says.
If a camera could see like a trilobite, Agrawal figured, it could capture high-quality images with higher depths of field. A high depth of field — the distance between the nearest and farthest points that a camera can bring into focus — is important for the relatively new technique of light-field photography, which uses many tiny lenses to produce 3-D photos.
To mimic the trilobite’s ability, the team constructed a metalens, a type of flat lens made up of millions of differently sized rectangular nanopillars arranged like a cityscape — if skyscrapers were one two-hundredth the width of a human hair. The nanopillars act as obstacles that bend light in different ways depending on their shape, size and arrangement. The researchers arranged the pillars so some light traveled through one part of the lens and some light through another, creating two different focal points.
To use the device in a light-field camera, the team then built an array of identical metalenses that could capture thousands of tiny images. When combined, the result is an image that’s in focus close up and far away, but blurry in between. The blurry bits are then sharpened with a type of machine learning computer program.
You can read more of the metalens research here, in Nature Communications.