These Smart Contact Lenses Overlay Info Without Obscuring Your View
Maybe our eyes really need head-up displays. For a company that until recently was in stealth mode, high-powered Mojo Vision hasn’t been shy about advertising its radical vision for the way we interact with computers. Skipping past all those bulky wearable designs and right into a science-fiction-worthy future it calls “invisible computing,” the company is developing smart contact lenses that can overlay information without obscuring your view of the world.
After five years and over $150 million raised, Mojo Vision is finally willing to talk a bit about how it is accomplishing that. No doubt it feels it has earned some running room, with over 100 patents issued or filed by its 85 employees. Their creation, the Mojo Lens, enables the projection of information directly into your retina. That means what you see in the real world can be augmented with overlays of various kinds. An image sensor, some built-in image processing, and a companion wearable will allow apps to provide a wide variety of augmented reality experiences.
Display Magic Is at the Heart of the Mojo Lens
The lenses use a tiny projector to send information to your retinas. The one the company demonstrated last year had a stunning 14,000 pixel-per-inch resolution and measured a total of .5 mm across. Individual pixels were slightly larger (1.8 microns) than those in the image sensor in a smartphone for comparison. It has to be that small because it’s in front of your eye. The company says it only blocks a small fraction of the total light entering your pupil (not your field of view, just brightness), on the order of 10 percent, so that it doesn’t impact your normal vision more than a typical pair of glasses.
Of course, projecting light isn’t enough. It needs to be focused on your retina. Intuitively, collimated light is an appealing solution. However, the physics don’t work at that scale. It’s just too small. Potential approaches involving lasers or microlenses run into the same issue, so the simplest approach would be a simple, single-element, lens. But that lens would have to be 5 mm thick, which would make it unwearable. So the company has developed a multi-element lens for what it describes as its “Femtoprojector.”
A Computer in Your Eye
As with many problems, the notion of sticking a small display in front of your eye is more involved than it first appears. For example, Mojo found that accurate, high-speed, eye tracking was essential. Otherwise projected objects would move all over our field of view as our eyes darted about. For anyone who has shelled out hundreds of dollars on a bulky eye-tracker for a research project, the idea of having it built into contact lenses is an impressive feat all by itself. Unlike a typical, complex, eye-tracking hardware device, because the lenses move with your eye, the only hardware required is the typical accelerometer/magnetometer/gyro setup.
Mojo Vision Fellow Dr. Brian Lemoff explained the numerous advantages of this approach when speaking to a virtual gathering of Stanford University’s SCIEN lecture series. First, you don’t need to worry about the viewer being in or out of a specific eyebox, as the projector and lens are always focused centered on the fovea, where the wearer is looking. It also makes it possible to place content in a scene overlaying real-world objects and have it not jump around. For example, if you want to display the names of the people you’re speaking with, you’d rather have them anchored near each person instead of moving when you looked around. Finally, because of its tiny size, the femtoprojector has a very large depth of focus (DOF), so that everything it projects is always in focus. That eliminates any issues with vergence/accommodation conflicts.
The prototype the company has been demonstrating uses a special pair of tethered pair of glasses to beam information to the display in the lens. The product version will still require another wearable to control it, to serve as a relay between the lenses and your phone. But it could come in a variety of form factors.
Mojo has no shortage of applications envisioned for its lenses. Company CTO and Co-founder Mike Weimer took us through a variety of possibilities. Many of them echo what other, more traditional, AR companies have been promoting for years: sports and location data overlays, names of people you’re speaking with, and real-time translation of signs or other text. However, the contact lens form factor opens the door to some additional possibilities, especially for the vision-impaired. Edges could be enhanced and objects could be identified, for example. Night vision could also be improved.
Mojo Recognizes Privacy Is Important
Mojo’s architecture is also designed around privacy. The image sensor is for assisting in vision tasks, not sharing photos or videos, and all processing of data can be done locally. Obviously there will be plenty of apps that interact with the cloud, so the company and developers will need to come up with transparent ways to have users understand what information may be getting shared while running them.
FDA Approval May Be the Long Pole in the Tent
Since contact lenses are all medical devices, they need to be approved by the FDA and prescribed by a physician in the U.S. Mojo Vision’s Senior VP Steve Sinclair explained to me that while they still have plenty of technical work to do on user experience and system integration, FDA approval may be the ultimate gating item on when they can bring Mojo Lenses to market. One amazing stat is that to help ensure it is safe to wear on your eye, the power budget for the entire device is 1.5 milliwatts or less.