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Curved lenses, like those in cameras or telescopes, are stacked in order to reduce distortions and resolve a clear image. That's why high-power microscopes are so big and telephoto lenses so long.
While lens technology has come a long way, it is still difficult to make a compact and thin lens (rub a finger over the back of a cellphone and you'll get a sense of how difficult). But what if you could replace those stacks with a single flat -- or planar -- lens?
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated the first planar lens that works with high efficiency within the visible spectrum of light -- covering the whole range of colors from red to blue. The lens can resolve nanoscale features separated by distances smaller than the wavelength of light. It uses an ultrathin array of tiny waveguides, known as a metasurface, which bends light as it passes through, similar to a curved lens.
The article's description of the lens sounds reminiscent of a Fresnel lens. Perhaps Soylentils more familiar with the field can comment?
(Score: 2) by cellocgw on Sunday June 05 2016, @07:56PM
Yes, that's my impression as well (that the current design is monochromatic). From what little I know of current metamaterial designs, the physical spacing of the layout only fits one wavelength. There's always some "bandwidth" the same way an FM receiver can handle a signal thats slightly off-center frequency, but that's about it.
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(Score: 2) by Fnord666 on Monday June 06 2016, @02:45PM