This Weeks Topic: Contact lens AR/VR

Contact lens eye finger thumb black background 1068x601

At Dimension10 we like to be inspired by companies driving technological innovation. The companies who drive innovation are often brave risk-takers, who are mocked or discredited, as if the work they are doing is infeasible. Despite people like me sometimes pointing out things being difficult or even impossible, there will be companies out there to prove us wrong.

Published 11/06/2020 by Christer-André

Today, and in coming articles, I want to write about some XR-related tech that is being promised or wished for that, frankly, might be a little harder to achieve than people think. Before I get into this I want to acknowledge that there have been points in history where technology has been so disruptive that it has been impossible to predict.

In the early days of computing, a more powerful machine meant a bigger one. That is why science fiction often described building-sized computers or even planet-sized. One of the most impactful breakthroughs in modern history was the invention of photolithography.

This meant you could miniaturize circuits and computer components down from something as large as a lightbulb down to something that is not even visible to the human eye. Imagine the overhead projector many people have seen in presentations

Pirna DDR Museum Polylux

By clever use of optics, you can write something tiny on transparent paper, and it will appear much larger on the screen. Simple and smart.

Let's say you reverse this so that the projected image is smaller than what you wrote. Much smaller.
With the proper optics, and a light-sensitive surface (that the light will imprint on) you can effectively write the entire text of encyclopedia Britannica onto the surface of one grain of rice.

Essentially what processor manufactures do, is design an "architecture" for the processor, and project it onto a semiconductor surface. It is far more complex, involving different chemicals and such,
but - this is essentially how they are able to put tens of billions of transistors in stamp-sized surface.

Transistors are almost like switches and are basically what drives the logic, the 1s and 0s. This is the very foundation of the modern computer.

This is an incredibly fascinating topic, but let me stop myself before diving too deep into it. What I'm saying here, is that before this method was invented and proven - I might very well have been one of those highly skeptical of computers ever becoming smaller. Let's hope I'm wrong in some of my skepticism, after all it's just an educated guess and things can be turned on its head like the example of photolithography.

With that out of the way, here comes one of the things I think will be difficult to achieve:

Contact lens AR/VR

Comfort

You have to put them directly on your eyeballs. Even many people who rely on contacts in the real world, to see anything at all, want to get rid of them. Putting them on your eyes just to have ar-capabilities will be a tall mountain to climb for a large portion of people.

Sharpness

How sharp a display looks, is determined largely by its pixels per inch or PPI. A typical 50-inch tv has around 40-100ppi. Mojo Visions prototype for their AR-contact lens has a whopping 14 thousand PPI. That sounds very promising, only until you realize that the display is 0.5mm wide. Some simple math will then tell you that the resolution of the image produced, though impressive, only comes up to around 200x200 pixels. Far away from high definition, it is actually a significantly poorer resolution than old fashioned VHS-tapes.
On top of that, their display is only monochrome and displays green color only. It is actually highly comparable to the ridiculed Nintendo Virtual Boy from 1995.

Vboy

This interesting piece of VR history deserves an article on its own.

In practice, this means that in order to be useful for anything other than text and basic information, its resolution would have to be increased by a factor of 10.

Kontaktlinse

Blocking your view

As seen in the picture above, the actual display shown is not transparent. The part that creates the image is actually blocking what's behind it. This means it has to stay so small it only ever fills a small portion of your vision, or else you won't see anything else.
For it to actually be transparent, yet high resolution, we are actually potentially hitting some solid barriers in the laws of physics.

One of these barriers is that all lenses are a diffraction-limited system.This simply defines how there is a limit to how small of an area you can focus light on. On a very small scale, light behaves strangely and interferes with itself. Especially passing through glass or other transparent materials.

You get a phenomenon called airy discs. To get around this, you have to make the sensor and lens bigger. Essentially, each pixel on the sensor needs to be bigger than the smallest possible airy disc in order for it not to "leak" onto the pixel beside it. Enlarging the device is a challenge, well, at least it is with a device sitting directly on your eyeball.


Focal point

Similar to the above challenges, it is very hard to make an ultra-small lens that is able to focus at a close distance while also letting you focus far away. This is the reason why you cannot put your finger directly on the camera on your phone and see your own fingerprints. At least not while also seeing a sharp background.In the case of an AR-contact lens, the display is not even sitting right on top of the lens - but inside it. Maintaining a sharp display of the AR-content, filling your field of vision while maintaining sharpness of your surroundings is close to, if not impossible.


No tracking

In order to provide a full augmented reality experience, you also need to track the users head relative to the real world. With the absence of external sensors, you would have to have cameras inside the lens to provide computer vision for inside-out-tracking. This is extremely difficult to do with today's available technology on such a small scale.Even if that would be possible, the problem remains that the actual display part of the lens is too small to move the images around your eye. This would have to follow your eye, and rather than feeling like its floating in the world, it would feel like you had text fixed on a stick, that is then fixed to your eye.


Moores Law

Moores Law predicted that the density of transistors in a circuit would roughly double every two years. For many decades, this prediction has been remarkably accurate.However, the transistors we spoke about earlier in the article is approaching atom size. At some point in the not so distant future, we will no longer be able to make them smaller. Making electronics smaller is, therefore, going to be a lot harder and is currently unknown territory. With the slow evolution of batteries, the need for wireless transmitters and cameras. It is going to be a very tough job to actually build this into a contact lens in a safe way.


In conclusion, I would predict that full-fledged AR-contact lenses are not likely to even get close to working within the next 10 years. You might get a heads up display and some small information like text or small images, but - that's it.
With that said, would love for Mojo Vision to prove us wrong!