In January 2024, after decades of intermittent improvements in virtual reality (VR) and augmented reality (AR) devices failing to help the technology catch on with the public, tech behemoth Apple (Cupertino, CA, USA) launched its marketing of a headset with by far the highest resolution and sharpest contrast of any commercially available device to date [
1]. Yet sales of the Vision Pro (
Fig. 1), Apple’s much anticipated first entry in the VR/AR marketplace, have fallen far short of the company’s already low expectations [
2].
The Vision Pro’s retail price of 3499 USD, user discomfort, and a lack of compelling apps have been cited as the primary culprits for weak consumer demand. Apple now faces finding less expensive ways to build such a device, dealing with the headaches and motion sickness users have reported, and encouraging developers, who now have the headset in hand, to create the apps that could help establish the Vision Pro and succeeding devices as must-have consumer products, like the iPhone first released a decade and a half ago [
3].
While VR headsets, which generally resemble a helmet or oversized ski goggles, envelop a person’s field of vision, blocking their view of the real world, AR-only wearables typically take the form of a pair of eyeglasses that superimpose digital images onto a user’s view of the real world. Examples of AR applications include tutorials for home repairs, displaying driving directions, finding places to shop or eat, or augmented tours of notable places. But widespread adoption of any of these devices has not materialized. Many of the biggest names in tech have launched AR or VR/AR product lines. Google Glass, Microsoft’s HoloLens, and the three generations of Meta Quest have all failed to muster much more than modest consumer interest. With a display far superior to any device that has come before, the Vision Pro is a VR/AR headset and Apple’s first new product category since the 2014 launch of the Apple Watch. Calling it a “spatial computer,” Apple has pitched the device to consumers as a better way to watch movies, view photos, read, create art, and connect with other people [
4].
For AR simulations, like with AR glasses, the Vision Pro projects digital content onto a user’s real-world surroundings. However, like with Meta Quest 3 headset which retails for 499 USD (
Fig. 2), instead of using a direct view through glasses, cameras embedded in the Vision Pro headset re-create a user’s surroundings on a pair of screens—one for each eye. The headset then overlays digital content on those screens—for example, a live stream from a friend’s birthday party across town.
Each of the Vision Pro’s twin micro-organic light-emitting diode (OLED) displays measure 8.4 cm
2—about the size of a large postage stamp—and contain more than 11 million pixels spaced only 6.3 µm apart [
5]. These displays provide much higher resolution and sharper contrast than the far less expensive liquid crystal display (LCD) screens found in other marketed headsets, including the Meta Quest 3 [
5].
While the improvement in resolution is impressive, there are other factors to consider that determine the effectiveness of such tiny displays, said John Semmen, a graduate student in optics and photonics who works on display technology at the University of Central Florida in Orlando, FL, USA. Semmen said the holy grail of VR/AR displays might be related to properties other than resolution. “There are a number of components that go into fooling the human eye into seeing something that looks real, including contrast ratio, the depth at which the image is generated, and even the field of view.”
At nearly 400 USD each, the Vision Pro’s micro-OLED displays are the most expensive hardware component in the device, accounting for 23% of its total cost [
5]. The price is high because the precision required to build the displays means production in a foundry, a specialized chip-manufacturing facility. Per unit costs could come down as manufacturers move to pack more of the displays on larger pieces of silicon; micro-OLED makers are currently exploring a shift from 20 cm wafers to 30 cm wafers, which is the standard in today’s most advanced, high-volume silicon manufacturing [
5].
The Vision Pro’s pixel-dense displays are the product of years of work by Sony Semiconductor Solutions (Kanagawa, Japan), which makes the displays for Apple. The Sony division’s micro-OLED efforts, begun more than a decade ago, initially focused on developing colorful high-resolution digital viewfinders for cameras and head-mounted devices for viewing 3D movies at home [
5]. One key innovation that reduced the pixel pitch—the distance between pixels—to 6.3 µm involved placing the devices’ color filter closer to the OLED; this improved the viewing angle of each pixel, enabling a smaller display without compromising image quality [
5].
In another, somewhat unusual innovation that has met with mixed reviews [
6], [
7], [
8], Apple engineers installed an external-facing, flexible OLED screen on the front of the Vision Pro headset that displays a constantly updated representation of its user’s eyes. Apple claims that this feature, called EyeSight, offers “critical social cues about gaze” to people around the user [
9]. “They basically add your face on the outside,” said Yuqiang Ding, another graduate student in optics and photonics at the University of Central Florida.
Despite all the new technology—Apple filed more than 5000 patents for work that went into the Vision Pro [
10]—the demand for the headset has been weak. Apple is rumored to have sold hundreds of thousands of the 3499 USD units in the first couple of days after pre-orders opened [
11]. However, a sizable portion of users returned the device within several weeks of purchase, complaining that the headset brought on headaches and triggered motion sickness. Another complaint is the Vision Pro’s 680 g weight and the fact that most of it is front loaded [
12]. “If you want to really use it for a relatively long time, the weight is so important,” Ding said. “If you do not feel comfortable, that is a major problem.”
Apple has not released official figures on how many units it has sold or how many have been returned. But market analyst firm International Data Corporation (IDC) claims Apple sold fewer than 100 000 units over the first three months, with a 75% drop-off expected in subsequent quarters [
2]. However, a more important goal for Apple may have been to get the device into the hands of app developers [
13], [
14]. Those developers now have until the latter half of 2025 to prepare their apps before Apple’s rumored launch of a “budget” Vision Pro model with fewer features, including, perhaps, no EyeSight [
14].
Across the entire product class globally, about nine million VR and AR headsets were shipped in 2022 [
15]. The sales leader that year was the 499 USD Quest 3. However, Meta’s Reality Labs, the company’s division that makes the device, still recorded an operating loss of nearly 4 billion USD in the first quarter of 2023 [
16]. The near future could be brighter, though, with one market analysis firm optimistically forecasting total VR and AR device sales to accelerate over the 2023-2027 period at an annual growth rate of more than 30% [
17].
Despite their many strengths, micro-OLEDs, like those used in the Vision Pro displays, still have some shortcomings. While micro-OLEDs are excellent for displaying moving images, such as movies, they are suboptimal for showing static text [
5]. Also, the organic molecules inside micro-OLED displays can degrade over time, a phenomenon known as burn-in. It is unclear how long this issue might take to render the device unusable, but stress tests of other OLED devices have shown burn-in after 1500 h of use [
18].
In the pipeline to potentially replace micro-OLEDs are micro-light-emitting diodes (LEDs), which have superior display quality, increased longevity, less burn-in, and higher brightness that is easier to control [
5]. Mojo Vision (Saratoga, CA, USA) has developed micro-LED displays with a pixel pitch of just 1.87 µm, about one-third that of the Vision Pro’s displays [
19]. This extreme pixel density—more than 11 000 pixels per centimeter, crushing the micro-OLED record of nearly 4000 pixels per centimeter set a few years ago [
20]—may ultimately enable reductions in both the size and weight of VR/AR headsets. For comparison, the pixel densities of the Vision Pro’s micro-OLED displays and the Quest 3’s LCD screens are 1333 and 480 pixels per centimeter, respectively.
Like micro-OLEDs, micro-LEDs are manufactured monolithically, with the LEDs and the silicon backplane bonded in a production pipeline like that used to manufacture cutting-edge computer chips [
5]. This production approach has, until recently, yielded displays of just a single color (typically red, green, or blue). While efficient green- and blue-emitting LEDs have been around for years, red-emitting LEDs have posed more of a challenge. However, quantum dot technology has recently enabled the engineering of microscale LEDs that efficiently emit in the red spectrum [
21], suggesting that full-color monolithic micro-LED displays could be used in consumer devices soon. Mojo Vision, for example, unveiled a full-color red, green, and blue (RGB) micro-LED prototype with a 4 µm pixel pitch in January 2024 [
22]. The company is now working with DigiLens (Sunnyvale, CA, USA) to produce a slim, eyeglass form AR device [
19].
Shanghai, China-based Jade Bird Displays also recently, in August 2023, unveiled a full-color micro-LED prototype with a pixel pitch of 5 µm [
23]. In addition, researchers from the Georgia Institute of Technology (Atlanta, GA, USA) and the Massachusetts Institute of Technology (Cambridge, MA, USA) have developed a new process for vertically stacking freestanding, ultrathin RGB LED membranes, achieving a pixel pitch of 4 µm and the smallest-ever stack height—all while delivering a full range of colors [
24]. One unique aspect of the team’s process is that it allows the reuse of costly silicon wafers, which could significantly lower the cost of manufacturing smaller, thinner, and more realistic displays.
“We were not surprised that Apple went with micro-OLED because that technology has made a lot of progress, and it is just good enough that you can have real products right now,” said Hongxing Jiang, professor of electrical and computer engineering at Texas Tech University in Lubbock, TX, USA, and inventor of the micro-LED. “However, with the progress over the last several years and the color red now available, I believe that micro-LEDs will eventually replace micro-OLED displays in VR/AR applications.”
The key to the consumer-level production of micro-LED displays, said Jingyu Lin, Jiang’s micro-LED co-inventor and also a professor of electrical and computer engineering at Texas Tech, is driving vertically stacked RGB LEDs more efficiently. “Many research groups are designing complementary metal-oxide-semiconductors (CMOS) controllers to turn each layer on and off individually,” said Lin. That technology, which will provide efficient power consumption, minimal heat generation, and high performance, “is very, very close,” said Jiang. “In my mind, a CMOS-driven micro-LED display is the only way forward for these devices.”
PDF
(473KB)
