Retinal projection is a technology that uses your eye’s retina as a projection screen and beams light directly into your eye so that you see a “display” floating in space. It feels like it should be the future of VR, so what happened?
Understanding Virtual Retina Displays
All the flat panel displays you look at every day will have a pixel grid and then shine a backlight through that pixel grid, or the pixels themselves will emit light in the case of OLED displays.
Virtual Retinal Displays work more like the CRT (Cathode Ray Tube) monitors and TVs of the displayed days, where an image grid is drawn on the back of a phosphorescent screen. Except that in this case the image is drawn directly on the retina of the eye.
The end result is what appears to be a screen floating in space, or an image that appears to be part of the scene.
Why do we want retinal projection?
Retinal projection has a number of advantages over current display technologies. While early retinal projection systems were bulky and heavy, modern systems use lightweight laser systems or modern LED technology to shoot photons into your eyes.
Current VR headsets use one or more flat panel displays viewed through special lenses that disrupt the precisely distorted image on the LCD or OLED screen. This results in an image shaped to provide an immersive experience. Unfortunately, this design often results in visible pixel grids (the “chicken wire” or “screen door effect”) and slightly blurry images.
In contrast, the resolution and sharpness of retinal projection images are exceptional. They don’t cause the same amount of eye strain as OLEDs or LCD screens an inch from your eye, thanks to the small amount of light required.
Retinal projection systems also have optical advantages. This technology enables on-the-fly optical correction, so you don’t have to worry about wearing glasses. It can also refocus to display near or distant objects.
For VR or Mixed Reality (MR) headsets, retinal projection systems have the potential to create much smaller, less energy-consuming sets. The holy grail for any kind of VR or MR headset is to eventually shrink them down to the size of sunglasses.
The Limitations of Retinal Displays
There are a few limitations of retinal projection that make it less than ideal as a replacement for today’s VR systems. First of all, the field of view possible with the current retinal projection is too narrow for VR. This means it’s not immersive enough to meet the standards for modern VR experiences.
Retina displays use several approaches to project images into the eye, including advanced micro-mirror arrays or precisely angled lasers. Small moving parts like these are inevitably harder to make than solid-state systems like an OLED screen. That complex system under the hood creates many obstacles in the development process.
What happened to Avegant?
You may or may not know it, but there is actually a headset with retinal projection technology that you can buy and own. In 2016, a company called Avegant released the Avegant Glyph. The Glyph looks like a standard pair of headphones, but you can fold the headband over your eyes and enjoy a video feed projected onto your retina. It didn’t look like VR, but it was a 720p home theater system that you could take anywhere.
You can still buy a Glyph on Amazon, although it probably isn’t new. However, on Avegant’s site, you will not find a mention of the Glyph as a product that you can buy. Instead, Avegant sells “light engines” as components for other companies looking to develop wearable headsets. Even when the Glyph came out, reviewers were a bit lukewarm and it suffered from the typical first-generation technology syndrome. Reading contemporary reviews of the Glyph, reviewers noted that the headset was only 720p, heavy, tricky to set up at first and way too expensive for what it offers.
That said, Avegant is still here and working to advance its technology, perhaps so that a partner company (like Facebook perhaps) can one day create a successful mainstream system. And while Avegant is the only company we know of to have released a commercial VRD product, many different players are investing in research and development to realize VRD technology.
In 2020, Bosch showed off smartglasses that use lasers to project images onto your retina. QD Laser’s Viserium used retinal projection to help people with impaired vision see more clearly. Magic Leap is working on next-generation augmented reality, and the list of companies involved in VRD technology has at least half a dozen more names to add.
Retinal projection could be the future of mixed reality
While the current retinal projection may not be the best first for VR, it may have a future in MR applications. Devices like the Microsoft Hololens 2 incorporate laser-based projection of the retina and do not require a large field of view to be useful.
If retinal projection technology ever manages to achieve the same horizontal field of view as consumer VR headsets like the Quest 2, it could still be the most realistic and sharp VR solution, except you have to put a computer right into your visual cortex. stiches.
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