A team of engineers at MIT and the University of Massachusetts at Lowell have created something that, on the surface, seems impossible: they’ve designed a 180° fisheye lens from a single, 1mm-thin piece of calcium fluoride glass that is completely flat.
The creation—which they claim is “the first flat fisheye lens to produce crisp, 180-degree panoramic images—takes advantage of a bit of tech called metalenses, which are thought to be the next “giant leap” in optical technology.
Metalenses turn the optical paradigm on its head by combining flat lenses with “microscopic features” that manipulate the light rays as they enter the lens. Instead of using curvature, thickness, or some other characteristic of the glass element, a single flat piece of glass is covered in a precisely etched metasurface that does all of the light bending, allowing for wafer-thin lenses that can do the job of multiple glass elements all at once.
As MIT News explains, that’s exactly how the engineers were able to design this mm-thin fisheye lens:
In this case, the new fisheye lens consists of a single flat, millimeter-thin piece of glass covered on one side with tiny structures that precisely scatter incoming light to produce panoramic images, just as a conventional curved, multielement fisheye lens assembly would.
You can see the tiny lens for yourself in the photos below:
“This design comes as somewhat of a surprise, because some have thought it would be impossible to make a metalens with an ultra-wide-field view,” explains Juejun Hu, an associate professor at MIT and one of the paper’s authors. “The fact that this can actually realize fisheye images is completely outside expectation. This isn’t just light-bending — it’s mind-bending.”
What’s more, the engineers claim that this lens has already achieved “perfect imaging performance across almost the whole 180-degree view.” Mind-bending indeed.
For now the lens only works in the infrared spectrum, but the engineers are confident that it can be modified to work with visible light. If and when it is, we may begin to see fisheye or single-shot panorama lenses pop up in smartphones or (some day, we hope) packed inside a pancake style lens that’s no bigger than your lens cap.
The engineers published their breakthrough last Friday in the journal Nano Letters. To find out more, or if you want to dive into the details of how this metalens works and how it might be used in future optics, watch the video below or check out the full paper at this link.