The tech that pushes VR to the limits of the human eye

Big Tech wants us excited about the coming of the Metaverse, but today. virtual reality Hardware is a long way from achieving their lofty goals. One of the biggest challenges is building better displays with more pixels per inch, however Experts say New items and designs are on the way.

Silicon Valley is bidding for billions of dollars. IThe internet is about to work. His The biggest change since the advent of the smartphone. Before long, the thinking goes, most people are within reach. Web with wearable headsets that transport you into a virtual world instead of touching a touchscreen.

Today, virtual reality and augmented reality they are. Still fairly basic. While companies like Meta, Microsoft, Google, and Magic Leap are already selling virtual and augmented reality headsets, they’ve had limited use cases so far, and the experiences they offer still fall short of the high-quality standards we’ve come to expect. From digital entertainment.

One of the biggest limitations is the current display technology. In a VR headset, screens sit only a few centimeters in front of our eyes, so they have to pack a huge number of pixels into a small space to come close to the definition you’d expect from a modern 4K TV.

That’s impossible with today’s displays, but with PerApproximate Published last week in Science, Samsung and Stanford University researchers say Emerging technologies may soon push us to the theoretical limit of pixel density, resulting in powerful new VR headsets.

Efforts to improve display performance are complicated by the fact that this directly competes with another important goal. to do They are smaller, cheaper and more energy efficient. Today’s devices are bulky and unwieldy, limiting the time they are worn and the context in which they are used.

The main reason headphones are so big today is because of the array of optical elements they display and enough space between them and the display to focus light properly. New compact lens designs and metasurfaces—nanostructured films with unique optical properties—have allowed some breakthroughs in this area, the authors say, which may be at the limit.

New designs such as holographic lenses and “pancake lenses” that involve a layer of plastic or glass around the center can help reduce the lens-to-display distance by two to three times. But each of these connections reduces the brightness of the images, which needs to be compensated by more powerful and efficient displays.

Better displays are also needed to address another important limitation of today’s devices. ULtra-HD TV displays can achieve pixel densities of up to 200 pixels per degree (PPD) at a distance of 10 feet, which is more than the roughly 60 PPD that the human eye can detect. But when VR displays are at most an inch or two from the viewer’s eye, they can only achieve about 15 PPD.

To match the resolution range of the human eye, VR displays need to squeeze 7,000 to 10,000 pixels into each inch of display, the authors say. For context, the latest smartphone screens only manage about 460 pixels per inch.

Despite the size of that gap, there are already clear ways to close it. Currently, most VR headsets use separate red, green, and blue organic light-emitting diodes (OLEDs), which are difficult to overclock due to their manufacturing process. However, an alternative approach that adds colored filters to white OLEDs allows reaching 60 PPD.

Relying on filtering has its own problems, as it reduces the efficiency of the light source, resulting in low brightness or high power consumption. But it can get an experimental OLED design known as “meta-OLED”. ABy combining the light source with a nanopatterned mirror, they circumvent this trade-off by using resonance phenomena to emit light only at a certain frequency.

Meta-OLEDS can achieve pixel densities in excess of 10,000 ppd, reaching the physical limits set by the wavelength of light. They can be more efficient and have improved color definition compared to previous generations. However, despite the strong interest from display technology companies, the technology is still new and likely far from commercial.

Perhaps the most recent innovation in paintings, the authors say, is taking advantage of human biology. The eye can detect 60 PPD in the central part of the retina, known as the fovea, where the ability to perceive is very low. ohn around.

If eye movements can be accurately tracked, you only need to provide maximum definition in the part of the display that the user is looking at. While the improvements required in eye and head tracking add additional complexity to the designs, the authors say this is probably the innovation. It happens quickly.

It is important to remember that there is a host issues It’s not just better displays that need to be addressed if VR is to be widely marketed. In particular, powering these headphones poses complex challenges regarding battery capacity and the ability to dissipate heat on board electronics.

Also, the display technologies discussed by the researchers are primarily related to VR, not AR, whose headsets may rely on a different optical technology that does not obscure the view of the real world. Either way, the road map to get us there seems to be well underway, while more immersive virtual experiences still seem to be some way off.

Image credit: Harry Quan / Unsplash

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