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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: 0) by Anonymous Coward on Sunday June 05 2016, @12:06PM
What am I supposed to sense by rubbing a finger over the back of a cellphone?
(Score: 4, Interesting) by rleigh on Sunday June 05 2016, @12:29PM
I assume a bump as seen on current thin phones, which is required to accommodate the bulk of the optics (already miniaturised and making significant compromises in image quality).
If this does work as promised and is easy to scale up for bulk manufacture, it would be a revolution in optical engineering. Both for phones and other small devices--the "lens" could be laminated to the surface material and be small and unobtrusive, as well as cheaper. And also for serious optics like in microscopes, telescopes etc. In a good quality microscope, single lenses can cost several tens of thousands (and more); big telescope lenses are even more bulky and expensive. If you can replace these with something of comparable quality but which can be manufactured as a thin film, you could make billions.
As someone else mentioned, chromatic and other aberrations might be something which needs more investigation. Glass lenses already make compromises to accommodate different wavelengths--they are only optimal at a single wavelength. Does this technology eliminate or reduce the problem, or is it worse?
Either way, it certainly promises to be exciting for some applications, even if those applications are initially limited.
(Score: 0) by Anonymous Coward on Sunday June 05 2016, @01:05PM
My guess -- the first big applications will be for spy satellites. The telescope mirrors they use now are fabricated from glass (or other materials) with internal cutouts to save launch weight.