Here's why Apple and its competitors are using a highly specialized version of OLED for virtual reality.

At WWDC 2023, Apple announced the Vision Pro, an AR/VR headset that offers an impressive amount of technology, and an equally imposing $3,499 price tag. One of the things that helps the Vision Pro stand out from cheaper products from Valve and Meta is the use of a new type of display called micro-OLED. More than just a rebranding by the marketing experts at Apple, micro-OLED is a variation on the screen technology that's become a staple of best TV lists over the last few years.

Micro-OLED's main difference from "traditional" OLED is right in the name. Featuring far smaller pixels, micro-OLED has the potential for much, much higher resolutions than traditional OLED: think 4K TV resolutions on chips the size of postage stamps. Until recently, the technology has been used in things like electronic viewfinders in cameras, but the latest versions are larger and even higher resolution, making them perfect for AR and VR headsets.

Here's an in-depth look at this tech and where it could be used in the future.

What's OLED?
OLED stands for organic light-emitting diode. The term "organic" means the chemicals that help the OLED create light incorporate the element carbon. The specific chemicals beyond that don't matter much, at least to us end users, but suffice it to say when they're supplied with a bit of energy, they create light.

The benefit of OLED in general is that it creates its own light. So unlike LED LCD TVs, which currently make up the rest of the TV market, each pixel can be turned on and off. When off, they emit no light. You can't make an LED LCD pixel totally dark unless you turn off the backlight altogether, and this means OLED's contrast ratio, or the difference between the brightest and darkest part of an image, is basically infinite in comparison.

OLED TVs, almost all manufactured by LG, have been on the market for several years. Meanwhile, Samsung Display has recently introduced OLED TVs that also feature quantum dots (QD-OLED), which offer even higher brightness and potentially greater color. These QD-OLEDs are sold by Samsung, Sony, and, in computer monitor form, Alienware.

Micro-OLED, aka OLED on Silicon

Micro-OLED, also known as OLEDoS and OLED microdisplays, is one of the rare cases where the tech is exactly as it sounds: tiny OLED "micro" displays. In this case, not only are the pixels themselves smaller, but the entire "panels" are smaller. This is possible thanks to advancements in manufacturing, including mounting the display-making segments in each pixel directly to a silicone chip. This enables pixels to be much, much smaller.

If we take a look at Apple's claims, we can estimate how small these pixels really are. Firstly, Apple says the twin displays in the Vision Pro include "More pixels than a 4K TV. For each eye" or "23 million pixels." A 4K TV is 3,840x2,160, or 8,294,400 pixels, so that should equate to around 11,500,000 pixels per eye for the Apple screens.

Next, Apple partnered with Sony (or maybe TSMC) to create these micro-OLED displays and they are approximately 1 inch in size. To calculate the size of each pixel I'm going to use 32-inch 4K TVs as a comparison, and these boast about 138 pixels per inch. We don't know the aspect ratio of the chips in the Vision Pro, but if they're a square 3,400x3,400-pixel resolution that would be a total of 11,560,000 pixels, so that's a safe bet. So, if that's the case, these displays have a ppi of around 4,808(!) and that's more than almost anything else on the market, and that's by a lot. Even the high-resolution OLED screen on the Galaxy S23 Ultra has a ppi of "only" 500. Regardless of the panel's production aspect ratio, the ppi is going to be impressive. Apple didn't respond immediately to CNET's request for clarification.

AR and VR microdisplays are so close to your eyes that they need to be extremely high performance in order to be realistic. They need extreme resolution so you don't see the pixels, they need high contrast ratios so they look realistic, and they need high frame rates to minimize the chance of motion blur and motion sickness. In addition, being in portable devices means they need to be able to do all that with low power consumption. Micro-OLED seems able to do all of these, but at a cost. Literally a cost. The Vision Pro is the most high-profile use of the high-end of the technology and it costs $3,499.

Micro-OLED technology isn't particularly new, having been available in some form for over a decade. Sony has been using them in camera viewfinders for several years, as have Canon and Nikon. Like all display techs, however, micro-OLED has evolved quite a bit over the years. The displays in the Vision Pro, for instance, are huge and very high resolution for a micro-OLED display.

How is micro-OLED different from MicroLED? Despite the fact that they're written slightly differently, they are superficially similar in the way they are both self-emitting, or can make their own light. But on a more in-depth level, the differences between the carbon-based OLED and the non-carbon LED are sadly beyond the scope of this article. Suffice it to say right now, MicroLED is better suited for large, wall-sized displays using individual pixels made up of LEDs. Micro-OLED is better suited for tiny, high-resolution displays. This isn't to say that MicroLED can't be used in smaller displays, and we'll likely see some eventually. But for now they're different tools for different uses.

Where else will we see micro-OLED? At MWC 2023, Xiaomi announced its AR Glass Discovery Edition featured the technology, and future high-end VR headsets from Meta, HTC and others will likely use it. Currently, a company named Engo is using a tiny micro-OLED projector to display speed and other data on the inside of its AR sunglasses. I know I sure don't need these, but I want them. Then there's the many mirrorless and other cameras that have been using micro-OLED viewfinders for years.

Could we see ultra-ultra-ultra high-resolution TVs with this new technology? Technically, it's possible but highly unlikely. Macro micro-OLED is just OLED. The resolutions possible using more traditional OLED manufacturing are more than enough for a display that's 10 feet from your eyeballs. However, it's possible micro-OLED might find its way into wearables and other portable devices where its size, resolution and efficiency will be an asset. That's likely why LG, Samsung Display, Sony and others are all working on micro-OLED.

Will ultra-thin, ultra-high resolution micro-OLED displays compete in a market with ultra-thin, ultra-high resolution nanoLED? Could be. We shall see.

As well as covering TV and other display tech, Geoff does photo tours of cool museums and locations around the world, including nuclear submarines, massive aircraft carriers, medieval castles, epic 10,000-mile road trips and more. Check out Tech Treks for all his tours and adventures.

He wrote a bestselling sci-fi novel about city-size submarines and a sequel. You can follow his adventures on Instagram and his YouTube channel.