A lens-stippled glass dome that looks a little like something you’d find on a mutant Dalek in Doctor Who — that’s one way of describing an experimental digital camera designed to function like a bug’s eye by capturing high-resolution panoramas and continuous depth of field.
Scientists at the University of Illinois at Urbana-Champaign as well as the University of Colorado at Boulder wanted to mimic that sort of imaging system, one that could marry wide-angle field of view with enhanced motion perception and infinite depth of field, and all of that without optical distortions. Easier said than done: The trouble with existing digital technology is that it tends to be both orthogonal and inflexible. “In biology, everything is curvy,” quipped one of the project’s scientists, John Rogers, to science journal Nature.
In a human eye, a single lens focuses light onto the retina, which harbors individual photoreceptors (the “rods” and “cones” you may recall from Biology 101). But in insects, each photoreceptor gathers light and visual information discretely.
Imagine what we might be able to do if we had bulging, insect-like eyeballs, apportioned into dozens, hundreds, even thousands of discrete ommatidia (photoreceptors), each pointed in a slightly different direction, each sending a unique image to the brain — a hive of appositional (side-by-side) ocular sensors working in tandem, extremely sensitive to motion and able to fine-focus on distant as well as nearby objects simultaneously. It’s this sense of visual superiority (at certain tasks, anyway) in insects with compound eyes that fuels so many of our bug-anthropomorphized superhero fantasies. Think about all the comic book heroes (and yes, villains) over the years with extrasensory abilities modeled on insect behavior, say the uncanny visual acuity of a simple housefly — difficult to catch because of its preternatural sensitivity to motion. That ability to detect and almost presciently react to motion isn’t some weird, quasi-psychic sixth sense, it’s simply evolutionary biology.
In order to emulate that, the University of Illinois researchers placed 180 micro-lenses tethered to posts on an inflatable half-sphere to create an artificial “eye” with a wide field of view, capable of bringing nearby or distant objects into focus simultaneously.* And yes, you read that right: inflatable, which is how you get from flat to “curvy.” The micro-lenses were initially assembled on a flat surface, but connected to photoreceptor-like stalks made from an elastic polymer, which Rogers says the team inflated like a balloon, lending the overall “eye” its hemispheric, bug-like shape. It was the team’s ability to predict exactly how the material would stretch that allowed them to create distortion-free visuals, reports Nature.
By contrast, conventional camera lenses depend on a single lens to get the job done, and a typical wide-angle lens suffers from image distortion because light passing through its curved lens is captured by sensors on a flat surface. With this experimental “bug” lens, the team was able to create a light detection system that could take on the same curved shape as the lens, rendering distortion a non-issue.
“The most important and most revolutionizing part of this camera is to bend electronics onto a curved surface,” said University of Colorado professor and study co-lead Jianliang Xiao in a press release. “Electronics are all made of silicon, mostly, and silicon is very brittle, so you can’t deform the silicon. Here, by using stretchable electronics we can deform the system; we can put it onto a curved surface.”
No, you probably won’t find Canon, Nikon or Pentax offering a “bug eye” lens anytime soon, but the point was to prove this was possible and scalable, with potential future applications ranging from high-tech surveillance equipment to futuristic medical imaging devices.
Next up, the team wants to take a shot at imitating a dragonfly’s eyes, where the ommatidia in each eye number in the tens of thousands.
* If you want to see one of the more famous early examples of the latter expressed in film, check out this sequence from Orson Welles’ Citizen Kane, paying particular attention to the window blinds in the background.