Scientists have created a flat lens that can focus a continuous bandwidth of colors, from blue to green — the world’s first.
The lens’ creators, a group of scientists from Harvard University, are the same researchers who unveiled a flat lens made up of a super thin arrangement of nanopillars. But the breakthrough lens could focus just one color at a time.
The researchers went back into the lab and found a way to correct for chromatic dispersion. Different colors of light feature different wavelengths. They are bent at a variety of angles by a flat lens, so they focus at different distances — that’s chromatic dispersion.
“Traditional lenses for microscopes and cameras — including those in cell phones and laptops — require multiple curved lenses to correct chromatic aberrations, which adds weight, thickness and complexity,” Federico Capasso, a professor of applied physics at Harvard, said in a news release. “Our new breakthrough flat metalens has built-in chromatic aberrations corrections so that a single lens is required.”
Researchers altered the shape, width, distance, and height of the nanopillars, so all types of light, blue through green, would focus at the same distance.
By giving their flat lens more control over chromatic dispersion, scientists have broadened its applications in imaging, spectroscopy and sensing.
“By harnessing chromatic aspects, we can have even more control over the light,” said researcher Reza Khorasaninejad. “Here, we demonstrate achromatic flat lenses and also invent a new type of flat lens with reverse chromatic dispersion. We showed that one can break away from the constraints of conventional optics, offering new opportunities only bound by the designer’s imagination.”
The scientists described their optical breakthrough in the journal Nano Letters.
Filed Under: Rapid prototyping