This is going to get a bit technical but will do my best to pretend I know exactly what I’m talking about and simply making it accessible. Essentially, researchers in the US and Canada believe they have worked out a way to produce flat lenses through the use on titanium “nanofins” that provide comparable images to curved commercial lenses that non only skirt Fermat’s principle but can also be mass produced by the same foundries that produce microchips.
Fermat’s principle, and by nano we’re talking really little flat lenses
Imagine a lens thinner than a human hair and measures only two millimeters in diameter, which provides an image as detailed as the best in microscope lenses. Thanks to a team of researchers led by Dr. Federico and his colleagues at Harvard University their imaginations my aid yours. While you may have limited daily use for spectroscopy, microscopy, or laser-related imaging, the same technology could also cause a sea change in the lenses used in wearable technology and smartphones.
Fermat’s principle dictates that light follows the path of least resistance if you will, or at least it moves along a route where the least phase is accumulated. When its introduced to areas with higher refractive index it bends towards the normal in almost an inherent laziness as it looks to make a shorter journey where the phase accumulates quicker and the wavelength is shorter. Wave propagation causes continuous phase accumulation so lenses need to have a fixed thickness to bring the necessary phase to bare on a desired direction change.
Capasso and his colleagues, about five years ago, determined while the principle holds it can be given the “run around” by redirecting light by changing phase discontinuously though they did so with metallic antennas that were inefficient and difficult to make.
Making nanofins not terribly different than microchips
But now, they have figured out a way to fabricate “nanofins” with electron beam lithography to produce a metasurface.
“In my opinion, this technology will be game-changing,” said Federico Capasso of Harvard University, the senior author of a report detailing the nanofins that appears in the journal Science.
Essentially the metasurface is a layer of transparent quartz with millions of pillars coating its surface. The pillars each interact with light and the sheer volume of them allows a beam of light to by reshaped as it passes through providing the focus of a standard lens.
“The quality of our images is actually better than with a state-of-the-art objective lens. I think it is no exaggeration to say that this is potentially revolutionary.”
But that’s far from all. Present lens fabrication requires the same molding that existed in the 1800s though it has clearly been refined.
“But our lenses, being planar, can be fabricated in the same foundries that make computer chips. So all of a sudden the factories that make integrated circuits can make our lenses,” Capasso explained.
“Once you have the foundry – you want a 12-inch lens? Feel free, you can make a 12-inch lens. There’s no limit,” he continued.
Let’s be clear, this is still a long ways away but potentially revolutionary as you’ve seen.
The team just needs thousands of hours of computer modeling to determine the pillar placements, spacing and orientation (and a lot more than that).
It’s all a bit out there but it sounds as if they know what they are doing and what comes next. We’ll be waiting for more.
