Introduction

Based on information gathered at SID Display Week and AWE, I have many articles to write based on the thousands of pictures I took and things I learned. I have been organizing and editing the pictures.

As its name implies, Display Week is primarily about display devices. My major takeaway from that conference is that many companies work on full-color MicroLEDs with different approaches, including quantum dot color conversion, stack layers, and single emitter with color shifting based on current or voltage.

AWE moved venues from the Santa Clara Convention Center in Silicon Valley to the larger Long Beach Convention Center south of LA. More than just a venue shift, I sensed a shift in direction. Historically, at AWE, I have seen many optical see-through AR/MR headsets, but there seem to be fewer optical headsets this year. Instead, I saw many companies with software running on VR/Passthrough AR headsets, primarily on the Meta Quest 3 (MQ3)and Apple Vision Pro (AVP).

This article was partly inspired by Hypervision’s white paper discussing whether micro-OLEDs or small LCDs were the best path to 60 pixels per degree (PPD) with a wide FOV combined with the pictures I captured through Hypervision’s HO140 (140° diagonal FOV per eye) optics at AWE 2024. I have taken thousands of pictures through various headsets, and the Hypervision picture stood out in terms of FOV and sharpness. I have followed Hypervision since 2021 (see Appendix: More on Hypervision).

I took my first pictures at AWE through the Sony XR (SXR) Headset optics. At least subjectively, in a short demo, the SXR’s image quality (sharpness and contrast) seemed higher than that of the AVP, but the FOV was smaller. I had on hand (thousands) of pictures I had taken through the Big Screen Beyond (BSB), AVP, Meta Quest Pro (MQP), and Meta Quest 3 (MQ3) optics with the same camera and lens, plus a few of the Hypervision HO140 prototype. So, I decided to make some comparisons between various headsets.

I also want to mention LightPolymers’ new Quarter Waveplate (QWP) and Polarization technologies, which I first learned about from a poster in the Hypervision AWE booth. In April 2024, the two companies announced a joint development grant. They offer an alternative to the plastic film QWP and Polarizers, where 3M dominates today.

Hypervision’s HO140 Display

Based on my history of seeing Hypervision’s 240° prototypes for the last three years, I had, until AWE 2024, largely overlooked their single display 140° models. I had my Canon R5 (45Mp with 405mp ” 3×3 sensor pixel shift mode”) and tripod with me at AWE this year, so I took a few high-resolution pictures through the optics of the HO140. Below are pictures of the 240° (left) and 140° (right) prototypes in the Hypervsion Booth. Hypervision is an optics company and not a headset maker and the demos are meant to show off their optics.

When I got home and looked at the pictures through the HO140, I was impressed by the overall image quality of the HO140, after having taken thousands of pictures through the Apple Vision Pro (with Micro-OLED displays) and Meta’s Quest Pro, Quest 3 (both with mini-LCD displays), the Big Screen Beyond. It usually takes me considerable time and effort, as well as multiple reshoots, to find the “sweet spot” for the other devices, but I got good pictures through the HO140 with minimal effort and only a few pictures, which suggests a very large sweet spot in Hypervision’s optical design. The HO140 is a prototype of unknown cost that I am comparing to production products. I only have this one image to go by and not a test pattern.

The picture below is from my Canon R5, with a 16mm lens netting a FOV of 97.6° horizontal by 73.7° vertical. It was shot at 405mp and then reduced to 45mp to avoid moiré effects due to the “beat frequencies” between the camera sensor and the display devices with their color subpixels. All VR optics pincushion, which causes the pixel sizes to vary across the display and increases the chance of getting moiré in some regions.

The level of sharpness throughout the HO140’s image relative to other VR headsets suggests that it could support a higher-resolution LCD panel with a smaller pixel size if it existed. Some significant chroma aberrations are visible in the outer parts of the image, but these could be largely corrected in software.

Compared to other VR-type headsets I have photographed, I was impressed by how far out into the periphery of the FOV the image maintains sharpness while supporting a significantly larger FOV than any other device I have photographed. What I can’t tell without being able to run other content, such as test patterns, is the contrast of the display and optics combination.

I suggest also reading Hypervision’s other white papers on their Technology & Research page. Also, if you want an excellent explanation of pancake optics, I recommend Arthur Rabner’s, CTO of Hypervision, one-hour and 25-minute presentation on YouTube.

Sony XR (SXR)

Mechanical Ergonomics

AWE was my first time trying the new Sony XR (SXR) headset. In my CES 2024 coverage, I wrote about the ergonomic features I liked in Sony XR (and others compared to Apple Vision Pro). In particular, I liked the headband approach with the flip-up display, and my brief try with the Sony headset at AWE seemed to confirm the benefits of this design choice (which is very similar to the Lynx R1 headset), at least from the ergonomics perspective relative to the Apple Vision Pro.

Still, the SXR is still pretty big and bulky, much more so than the AVP or Lynx. Having only had a short demo, I can’t say how comfortable it will be in extended use. As was the case for the HO140, I couldn’t control the content.

“Enterprise” Product

Sony has been saying that this headset primarily aims at “enterprise” (= expensive high-end) applications, and they partner with Siemens. It is much more practical than the Apple Vision Pro (AVP). The support on the head is better; it supports users wearing their glasses, and the display/visor flips up so you can see the real world directly. There is air circulation to the face and eyes. The headset also supports adjustment of the distance from the headset to the eyes. The headset allows peripheral vision but does have a light shield for full VR operation. The headset is also supposed to support video passthrough, but that capability was not demonstrated. As noted in my CES article, the SXR headset put the pass-through cameras in a much better position than the AVP.

Display Devices and Image Quality

Both the AVP and SXR use ~4K micro-OLED display devices. While Sony does the OLED Assembly (applying the OLED and packaging) for its headset and the AVP’s display devices, the AVP reportedly uses a custom silicon backplane designed by Apple. The SXR’s display has ~20% smaller 6.3-micron pixels than the AVP’s 7.5-micron. The device size is also smaller. The size factors of the SXR favor higher angular resolution and a smaller FOV, as is seen with the SXR.

The picture below was taken (handheld) with my 45MP Canon R5 camera with a 16mm lens like the HO140, but because I couldn’t use a tripod, I couldn’t get a 405MP picture with the camera’s sensor shifting. I was impressed that I got relatively good images handheld, which suggests the optics have a much larger sweet spot than the AVP, for example. To get good images with the AVP requires my camera lens to be precisely aligned into the relatively small sweep spot of the AVP’s optics (using a 6-degree-of-freedom camera rig on a tripod). I believe the Apple Vision Pro’s small sweet spot and the need for eye-tracking-based lens correction, and not just for foveated rendering, are part of why the AVP has to be uncomfortably clamped against the user’s face.

Given that I was hand-holding both the headset and camera, I was rather surprised that the pictures came out so well (click on the image to see it in higher, 45mp resolution).

At least in my brief demo, the SXR’s optics image quality seems better than the AVP’s. The images seem sharper with lesser chroma (color) aberrations. The AVP seems heavily dependent on eye tracking to correct optics problems with the optics, but it does not always succeed.

Much more Eye Refief (enabling eye glasses) but lower FOV

I was surprised by how much eye relief the SXR optics afforded compared to the AVP and BSB, which also use Micro-OLED microdisplays. Typically, the requirement for high magnification of the micro-OLED pixels compared to LCD pixels inherently makes eye relief more difficult. The SXR magnifies less, resulting in a smaller FOV, but also makes it easier optically for them to support more eye relief. But note, taking advantage of the greater eye relief will further reduce the FOV. The SXR headset has a smaller FOV than any other VR-type headset I have tried recently.

Novel Sony controllers were not a hit

While I will credit Sony for trying something new with the controllers, I didn’t like finger trackpad and ring color are great solutions. I talked with several people who tried them, and no one seemed to like either controller. It is hard to judge control devices in a short demo; you must work with them for a while. Still, they didn’t make a good first impression.

VR Headset “Shootout” between AVP, MQP, Big Screen Beyond, Hypervision, and Sony XR

I have been shooting VR headsets with the Canon R5 with a 16mm lens for some time and built up a large library of pictures. For the AVP, Big Screen Beyond (BSB), and Meta Quest Pro (MQP), I had both the the headset and the camera locked down on tripods so I could center the lens in the sweet spot of the optics. For the Hypervision, while the camera and headset were on tripods, my camera was only on a travel tripod without my 6-degree-of-freedom rig and the time to precisely locate the headset’s optical sweet spot. The SXR picture was taken with my hand holding the headset and the camera.

Below are through-the-optics pictures of the AVP, BSB, MQP, Hypervision HO140, and SXR headsets, all taken with the same camera and lens combination and scaled identically. This is not a perfect comparison as the camera lens does not work identically to the eye (which also rotates), but it is reasonably close. The physically shorter and simpler 16mm prime (non-zoom) lens lets it get inside the eye box of the various headsets for the FOV it can capture.

FOV Comparison (AVP, SXR, BSB, HO140, MQ3/MQP)

While companies will talk about the number of horizontal and vertical pixels of the display device, the periphery of the display’s pixels are cut off by the optics, which tend to be circular. All the VR headset optics have a pincushion distortion, which results in higher resolution in the sweet spot (optical center), which is always toward the nose side and usually above the center for VR headsets.

In the figure below, I have overlaid the FOV of the left eye for the headsets on top of the picture HO140 image. I had to extrapolate somewhat on the image circles on the top and bottom as the headset FOVs exceeded the extent of the camera’s FOV. The HO140 supports up to a 2.9″ diagonal LCD (that does not exist yet), but they currently use a 2.56″ 2160×2160 Octagonal BOE LCD and are so far beyond the FOV of my camera lens that I used their information.

As can be seen, the LCD-based headsets of Hypervision and Meta typically have larger FOV than the micro-OLED-based headsets of AVP, Meta, and Sony. However, as will be discussed, the micro-OLED-based headsets have smaller pixels (angularly and on the physical display device).

Center Pixels (Angular Size in PPD)

Due to handholding the SXR and having pixels smaller than the AVP, I couldn’t get a super-high-resolution (405 mp) image from the center of the FOV and didn’t have the time to use a longer focal length lens to show the pixel boundaries. The SXR has roughly the same number of pixels as the AVP but a smaller FOV, so its pixels are angularly smaller than the AVP’s. I would expect the SXR to be near 60 pixels per degree (PPD) in the center of the FOV. The BSB has about the same FOV as the AVP but has a ~2.5K micro-OLED compared to the AVP’s ~4K; thus, the BSB pixels in the center are about 1.5x bigger (linearly). The Hypervision’s display has a slightly smaller center pixel pitch than the MQP (and MQ3) but with a massively bigger FOV.

The MQP (and the very similar MQ3) rotate the display device. To make it easier to compare the pixel pitches, I included a rotated inset of the MQP pixels to match the alignment of the other devices. Note that the pictures below are all “through the optics” and thus include the headset’s optical magnification. I have given the angular resolution in PPD for each headset. I have indicated the angular resolution (in pixels-per-degree, PPD) for each of the headset’s center pixels. For the center pixels pictures below, I used a 28mm lens to get more magnification to see sub-pixel detail for the AVP, BSB, and MQP. I only took 16mm lens pictures of the HO140 and, therefore, rescaled the image based on the different focal lengths of the lens.

The Micro-OLED base headsets require significantly more optical magnification than the LCD models. For example, the AVP has 3.2x (linearly) smaller display device pixels than the MQP, but after optics, the pixels are ~1.82x smaller. As a specific example, the AVP magnifies the display by ~1.76 more than the MQP.

Outer Pixels

I capture pixels from a similar (very approximately) distance from the optical center of the lens. The AVP’s “foveated rendering” makes it look worse than it is, but you can still see the pixel grid with the others. Of the micro-OLED headsets, the BSB and SXR seem to do the best regarding sharpness in the periphery. The Hypervision HO140 pixels seem much less distorted and blurry than any of the headsets, including the MQP and MP3, which have much smaller FOVs.

Micro-OLED vs. Mini-LCD Challenges

Micro-OLEDs are made by applying OLEDs on top of a CMOS substrate. CMOS transistors provide a high current per unit area, and all the transistors and circuitry are underneath the OLED pixels, so it doesn’t block light. These factors enable relatively small pixels of 6.3 to 10 microns. However, CMOS substrates are much more expensive per unit area, and modern semiconductor FABs limit of CMOS devices is about 1.4-inch diagonal (ignoring expensive and low-yielding “reticle stitched” devices).

A basic issue with OLEDs is that the display device must provide the power/current to drive each OLED. In the case of LCDs, only a small amount of capacitance has to be driven to change the pixel, after which there is virtually no current. The table on the right (which I discussed in 2017) shows the transistor mobility and the process requirements for the transistors for various display backplanes. The current need for an emitting display device like OLEDs and LEDs requires crystalline silicon (e.g., CMOS) or much larger thin-film transistors on glass. There are also issues of the size and resistivity of the wires used to provide the current and heat issues.

The OLED’s requirement for significant current/power limits how small the pixels can get on a given substrate/technology. Thin-film transistors have to be physically big to supply the current. For example, the Apple Watch Ultra Thin Film transistor OLED display has 326 PPI (~78 microns), which is more than 10x larger linearly (100x the area) than the Apple Vision Pro’s pixel, even though both are “OLEDs.”

Another issue caused by trying to support large FOVs with small devices is that the higher magnification reduces eye relief. Most of the “magnification” comes from moving the device closer to the eye. Thus, LCD headsets tend to have more eye relief. Sony’s XR headset is an exception because it has enough eye relief for glasses but does so with a smaller FOV than the other headsets.

Small LCDs used in VR displays have different challenges. They are made on glass substrates, and the transistors and circuitry must be larger. Because they are transmissive, this circuitry in the periphery of each pixel blocks light and causes more of a screen door effect. The cost per unit area is much lower than that of CMOS, and LCD devices can be much larger. Thus, less aggressive optical magnification is required for the same FOV with LCDs.

LCDs face a major challenge in making the pixels smaller to support higher resolution. As the pixels get smaller, the size of the circuitry relative to the pixel size becomes bigger, blocking more light and causing a worse screen door effect. To make the pixels smaller, they must develop higher-performance thin-film transistors and lower resistance interconnection to keep blocking too much light. This subject is discussed in an Innolux Research Paper published by SPIE in October 2023 (free to download). Innolux discusses how to go from today’s typical “small” LCD pixel of 1200 ppi (=~21 microns) to their research device with 2117 ppi (=~12 microns) to achieve a 3840 x 3840 (4K by 4k) display in a 2.56″ diagonal device. Hypervision’s HO140 white paper discusses Innolux’s 2022 research prototype with the same pixel size but with 3240×3240 pixels and a 2.27-inch panel, as well as the current prototype. The current HO140 uses a BOE 2.56″ 2160×2160 panel with 21-micron pixels, as the Innolux panel is not commercially available.

Some micro-OLED and small LCD displays for VR

YouTuber Brad Lynch of SadlyItsBradley, in an X post, listed the PPI of some common VR headset display devices. I have added more entries and the pixel pitch in microns. Many VR panels are not rectangular and may have cut corners on the bottom (and top). The size of the panels given in inches is for the longest diagonal. As you can see, Innolux’s prototypes have significantly smaller pixels, but almost 2x linearly, than the VR LCDs in volume production today:

• Vive: 3.6″, 1080p, ~360 PPI (70 microns)
• Rift S*: 5.5″, 1280P, ~530 PPI (48 microns)
• Valve Index: 3.5″, 1440p, ~600 PPI (42 microns)
• Quest 2*: 5.5″, 1900p, ~750 PPI (34 microns)
• Quest 3: ~2.55″ 2064 × 2208, 1050 PPI (24 microns) – Pancake Optics
• Quest Pro: 2.5″, 1832×1920, ~1050 PPI (24 microns) – Might be BOE 2.48″ miniLED LCD
• Varjo Aero: 3.2″, 2880p, ~1200 PPI (21 microns)
• Pico 4: 2.5″, 2160p, 1192 PPI (21 microns)
• BOE 2.56″ LCD, 2160×2160, 1192 PPI (21 microns) – Used in Hypervision HO140 at AWE 2024
• Innolux 2023 Prototype 2.56″, 3840×3840, 2117 ppi (12 microns) -Research prototype
• Apple Vision Pro 1.4″ Micro-OLED, 3,660×3,200, 3386 PPI (7.5 microns)
• SeeYa 1.03″ Micro-OLED, 2560×2560, 3528 PPI (7.2 microns) – Used in Big Screen Beyond
• Sony ~1.3″ Micro-OLED, 3552 x 3840, 4032 PPI (6.3 microns) – Sony XR
• BOE 1.35″ Micro-OLED 3552×3840, 4032 PPI (6.3 microns) – Demoed at Display Week 2024

In 2017, I wrote Near Eye Displays (NEDs): Gaps In Pixel Sizes (table from that article on the right) talks about what I call the pixel size gap between microdisplays (on Silicon) and small LCDs (on glass). While the pixel sizes have gotten smaller for both micro-OLED and LCDs for VR in the last ~7 years, there remains a sizable gap.

Contrast – Factoring the Display and Pancake Optics

Micro-OLEDs at the display level certainly have a better inherent black level and can turn pixels completely off. LCDs work by blocking light using cross-polarization, which results in imperfect blacks. Thus, with micro-OLEDs, a large area of black will look black, whereas with LCDs, it will be dark gray.

However, we are not looking at the displays directly but through optics, specifically pancake optics, which dominate new VR designs today. Pancake optics, which use polarized light and QWP to recirculate the image twice through parts of the optics, are prone to internal reflections that cause “ghosts” (somewhat out-of-focus reflections) and contrast loss.

Using smaller micro-OLEDs requires more “aggressive” optical designs that support higher magnification to support a wide FOV. These more aggressive optical designs can be more prone to being more expensive, less sharp, and loss of polarization. Any loss of polarization in pancake optics will cause a loss of contrast and ghosting. There seems to be a tendency with pancake optics for the stray light to bounce around and end up in the periphery of the image, causing a glow if the periphery of the image is supposed to be black.

For example, the AVP is known to have an outer “glow” when watching movie content on a black background. Most VR headsets default to a “movie or home theater” rather than a background. While it may be for aesthetics, the engineer in me thinks it might help hide the glow. People online suggest turning on some background with the AVP for people bothered by the glow on a black background.

The complaints of outer glow when watching movies seem more prevalent when using headsets micro-OLEDs, but this is hardly scientific. It could be just that the micro-OLEDs have a better black level and make the glow more noticeable, but it might also be caused by their more aggressive optical magnification (something that might be or has been (?) studied). My key point is that it is not as simple as considering the display’s inherent contrast, you have to consider the whole optical system.

LightPolymers’ Alternative to Plastic Films for QWP & Polarizers

LightPolymers has a Lyotropic (water-based) Liquid Crystal (LC) material that can make optical surfaces like QWP and polarizers. Silicon Optix, which the blog broke the news of Meta buying them in December 2021 (Exclusive: Imagine Optix Bought By Meta), was also developing LC-based polarized light control films.

Like Silicon Optix, Light Polymers has been coating plastic films with LCs, but LightPolymers is developing the ability to directly apply their films to flat and curved lenses, which is a potential game changer. In April 2024, LightPolymers and Hypervision announced the joint development of this lens-coating technology and had a poster in their Hypervision’s booth showing it (right)

3M Dominates Polarized Light Plastic Films for Pancake Optics

3M is today the dominant player in polarized light-control plastic films and is even more dominant in these films for pancake optics. At 3M’s SID Display Week booth in June 2024, they showed the ByteDance PICO4, MQP, and MQ3 pancake optics using 3M polarization films. Their films are also used in the Fresnel lens-based Quest 2. It is an open secret (but 3M would not confirm or deny) that the Apple Vision Pro also uses 3M polarization films.

According to 3M:

“3M did not invent the optical architecture of pancake lenses. However, 3M was the first company to successfully demonstrate the viability of pancake lenses in VR headsets by combining it with its patented reflective polarizer technology.“

That same article supports Kopin’s (now spun out to Lightning Silicon) claims to have been the first to develop pancake optics. Kopin has been demonstrating pancake optics combined with their Micro-OLEDs for years, which are used in Panasonic-ShiftAll headsets.

3M’s 2017 SPIE Paper Folded Optics with Birefringent Reflective Polarizers discusses the use of their films (and also mentions Kopin developments) in cemented (e.g., AVP) and air gap (e.g., MQP and MP3) pancake optics. The paper also discusses how their polarization films can be made (with heat softening) to conform to curved optics such as the AVP.

LightPolymers’ Potential Advantage over Plastic Films

The most obvious drawbacks of plastic films are that they are relatively thick (on the order of 70+ microns per film, and there are typically multiple films per lens) and are usually attached using adhesive coatings. The thickness, particularly when trying to conform to a curved surface, can cause issues with polarized light. The adhesives introduce some scatter, resulting in some loss of polarization.

By applying their LCs directly to the lens, LightPolymer claims they could reduce the thickness of the polarization control (QWP and Polarizers) by as much as 10x and would eliminate the use of adhesives.

In the photos below (taken with a 5x macro lens), I used a knife to slightly separate the edges of the films from the Meta Quest 3’s eye-side and display-side lenses to show them. On the eye-side lens, there are three films, which are thought to be a QWP, absorptive polarizer, and reflective polarizer. On the display-side lens, there are two films, one of which is a QWP, and the other may be just a protective film. In the eye-side lens photo, you can see where the adhesive has bubbled up after separation. The diagram on the right shows the films and paths for light with the MQ3/MQP pancake optics.

Because LighPolymers’ LC coating is applied to each lens, it could also be applied/patterned to improve or compensate for other issues in the optics.

Current State of LightPolymer’s Technology

LightPolymers is already applying its LC to plastic films and flat glass. Their joint agreement with Hypervision involves developing manufacturable methods for directly applying the LC coatings to curved lens surfaces. This technology will take time to develop. LightPolymer business of making the LC materials and then works with partners such as Hypervision to apply the LC to their lenses. They say the equipment necessary to apply the LCs is readily available and low-cost (for manufacturing equipment).

Conclusion

Hypervision has demonstrated the ability to design very wide FOV pancake optics with a large optical sweet spot and maintains a larger area of sharpness than any other design I have seen.

Based on my experience in both Semiconductors and Optics, I think Hypervision makes a good case in their white paper 60PPD: by fast LCD but not by micro OLED, getting to a wide FOV while approaching “retinal” 60PPD is more likely to happen using LCD technology than micro-OLEDs.

Fundamentally, micro-OLEDs are unlikely to get much bigger than 1.4″ diagonally, at least commercially, for many years, if not more than a decade. While they could make the pixels smaller, today’s pancake optics struggle to resolve ~7.5-micron pixels, no less small ones.

On the other hand, several companies, including Innoulux and BOE, have shown research prototypes of 12-micron LCD pixels, or half the (linear) size of today’s LCDs used in VR headsets in high volume. If BOE or Innolux went into production with these displays, it would enable Hypervision’s HO140 to reach about 48 PPD in the center with a roughly 140-degree FOV, and only small incremental changes would get them to 60 PPD with the same FOV.

Appendix: More on Hypervision

I first encountered Hypervision at AWE 2021 with their blended Fresnel lens 240-degree design, but as this blog primarily covered optical AR, it slipped under my radar. Since then, I have been covering Optical and Pass-Through mixed reality, particularly pass-through MR using Pancake Optics. By AR/VR/MR 2023, Hypervsion demonstrated a single lens (per eye) 140-degree and a blended dual lens and display 240-degree FOV (diagonal) Pancake Optics designs.

These were vastly better than their older Fresnel designs and demonstrated Hypervision’s optical design capability. In May 2023, passthrough MR startup Lynx and Hypervision announced they were collaborating. For some more background on my encounters with Hypervision, see Hypervision Background.

Hypervision has been using its knowledge of pancake optics to analyze the Apple Vision Pro’s optical design, which I have reported on in Hypervision: Micro-OLED vs. LCD – And Why the Apple Vision Pro is “Blurry,” Apple Vision Pro Discussion Video by Karl Guttag and Jason McDowall, Apple Vision Pro – Influencing the Influencers & “Information Density,” and Apple Vision Pro (Part 4)—Hypervision Pancake Optics Analysis.

Introduction

As discussed in Mixed Reality at CES and the AR/VR/MR 2024 Video (Part 1 – Headset Companies), Jason McDowall of The AR Show recorded over four hours of video discussing the 50 companies I met at CES and AR/VR/MR. The last thing we discussed for about 50 minutes was the Apple Vision Pro (AVP).

The AVP video amounts to a recap of the many articles I have written on the AVP. Where appropriate, I will give links to my more detailed coverage in prior articles and updates rather than rehash that information in this article.

It should be noted that Jason and I recorded the video on March 25th, 2024. Since then, there have been many articles from tech magazines saying the AVP sales are lagging, often citing Bloomberg’s Mark Gurman’s “Demand for demos is down” and Analyst Ming Quo reporting, “Apple has cut its 2024 Vision Pro shipments to 400–450k units (vs. market consensus of 700–800k units or more).” While many reviewers cite the price of the AVP, I have contended that price was not the problem as it was in line with a new high-tech device (adjusted for inflation, it is about the same price as the first Apple II). My criticism focuses on the utility and human factors. In high-tech, the cost is usually a fixable problem with time and effort, and people will pay more if something is of great utility.

I said the Apple Vision Pro would have utility problems before it was announced. See my 2023 AWE Presentation “Optical Versus Passthrough Mixed Reality“) and my articles on the AVP. I’m not about bashing a product or concept; when I find faults, I point them out and show my homework, so to speak, on this blog and in my presentations.

Before the main article, I want to repeat the announcement that I plan to go to DisplayWeek in May and AWE in June. I have also included a short section on YouTube personality/influence Marques Browlee’s Waveform Podast and Hugo Barra’s (former Head of Oculus at Meta) blog article discussing my controversial (but correct) assessment that the Apple Vision Pro’s optics are slightly out of focus/blurry.

DisplayWeek and AWE

I will be at SID DisplayWeek in May and AWE in June. If you want to meet with me at either event, please email meet@kgontech.com. I usually spend most of my time on the exhibition floor where I can see the technology.

AWE has moved to Long Beach, CA, south of LA, from its prior venue in Santa Clara, and it is about one month later than last year. Last year at AWE, I presented Optical Versus Passthrough Mixed Reality, available on YouTube. This presentation was in anticipation of the Apple Vision Pro.

At AWE, I will be on the PANEL: Current State and Future Direction of AR Glasses on Wednesday, June 19th, from 11:30 AM to 12:25 PM with the following panelists:

• Jason McDowall – The AR Show (Moderator)
• Jeri Ellsworth – Tilt Five
• Adi Robertson – The Verge
• Edward Tang – Avegant
• Karl M Guttag – KGOnTech

There is an AWE speaker discount code – SPKR24D , which provides a 20% discount, and it can be combined with Early Bird pricing (which ends May 9th, 2024). You can register for AWE here.

“Controversy” of the AVP Being a Little Blurry Discussed on Marques Brownlee’s Podcast and Hugo Barra’s Blog

As discussed in Apple Vision Pro – Influencing the Influencers & “Information Density,” which included citing this blog on Linus Tips, this blog is read by other influencers, media, analysts, and key people at AR/VR/MR tech companies.

Marques Brownlee (MKBHD), another major YouTube personality, Waveform Podcast/WVFRM YouTube channel, discussed (link to the YouTube discussion) my March 1st article on Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3. Marques discussed Hugo Barra’s (former Head of Oculus at Meta) blog’s March 11, 2024 “Hot Take” article (about 1/3rd of the way down) on my blog article.

According to MKBHD and Hugo Barra, my comments about Vision Pro are controversial, but they agree that it would make sense based on my evidence and their experience. My discussion with Jason was recorded before the Waveform Podcast came out. I’m happy to defend and debate this issue.

Outline of the Video and Additional Information

The Video The times in blue on the left of each subsection give the link to the YouTube video section discussing that subject.

00:16 Ergonomics and Human Factors

I wrote about the issues with the AVP’s human factors design in Apple Vision Pro (Part 2) – Hardware Issues Mechanical Ergonomics. In a later article in CES Part 2, I compared the AVP to the new Sony XR headset in the Sony XR (and others compared to Apple Vision Pro) section.

08:23 Lynx and Hypervision

I wrote the article comparing the new Sony XR headset to the AVP mentioned the Lynx R1, first shown in 2021, in this comparison. But I didn’t realize how much they were alike until I saw a post somewhere (I couldn’t find it again) by Lynx’s CEO, Stan Larroque saying how much they were alike. It could be a matter of form following function, but how much they are alike from just about any angle is rather striking.

While on the subject of Lynx and Apple. Lynx used optic by Limbak for the Lynx R1. As I broke in December 2022 Limbak Bought by “Large US Company” (which soon was revealed as Apple) and discussed in more detail in a 2022 Video with Brad Lynch, I don’t like the R1’s Limbak “catadioptric” (combined mirror and refractive) optics. While the R1 optics are relatively thin, like pancake optics, they cause a significant loss of resolution due to their severe distortion, and worse, they have an optical discontinuity in the center of the image unless the eye is perfectly aligned.

In May 2023, Lynx and Hypervision announced that they were working together. In Apple Vision Pro (Part 4)—Hypervision Pancake Optics Analysis, Hypervision detailed the optics of the Apple Vision Pro. That article also discusses the Hypervision pancake optics it was showing at AR/VR/MR 2023. Hypervision demonstrated single pancake optics with a 140-degree FOV (the AVP is about 90 degrees) and blended dual pancake optics with a 240-degree FOV (see below right).

10:59 Big Screen Beyond Compared to AVP Comfort Issues

When I was at the LA SID One Day conference, I stopped by Big Screen Beyond to try out their headset. I wore Big Screen’s headset for over 2 hours and didn’t have any of the discomfort issues I had with the AVP. With the AVP, my eyes start bothering me after about 1/2 hours and are pretty sore by 1 hour. There are likely two major factors: one is that the AVP is applying pressure to the forehead, and the other is that something is not working right optically with the AVP.

Big Screen Beyond has a silicon gel-like custom interface that is 3-D printed based on a smartphone face scan. Like the AVP, they have magnetic prescription inserts. While the Big Screen Beyond was much more comfortable, the face interface has a large contact area with the face. While not that uncomfortable, I would like something that breathed more. When you remove the headset, you can feel the preparation evaporating from where the interface was contacting your face. I can’t imagine anyone wearing makeup being happy (the same with the with the AVP or any headset that presses against the face).

On a side note, I was impressed by Big Screen Beyond’s statement that it is cash flow positive. It is a sign that they are not wildly spending money on frills and that they understand the market they are serving. They are focused on serving dedicated VR gamers who want to connect the headset to a powerful computer.

Related to the Big Screen Beyond interface, a tip I picked up on Reddit is that you can use a silicon face pad made for the Meta Quest 2 or 3 on the AVP’s face interface (see above right). The silicon face pad gives some grip to the face interface and reduces the pressure required to hold the AVP steady. The pad adds about 1mm, but it so happens that I had recently swapped my original AVP face interface for one that is 5mm shorter. Now, I barely need to tighten the headband. A downside to the silicon pad, like the Big Screen Beyond, is that it more or less forms a seal with your face, and you can feel the perspiration evaporating when you remove it.

13:16 Some Basic AVP Information

In the video, I provide some random information about the AVP. I wanted to go into detail here about the often misquoted brightness of the AVP.

I started by saying that I have read or watched many people state that the AVP is much brighter than the Meta Quest 3 (MQ3) or Meta Quest Pro (MQP). They are giving ridiculously high brightness/nits values for the AVP. As I reported in my March 7th, 2024, comments in the article Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3, the AVP outputs to the eye about 100 nits and is only about 5-10% brighter than the MQ3 and ~20% less than the MQP.

I will explain how this came about in the Appendix at the end. And to this day, if you do a Google search (captured below), it will prominently state that the AVP has a “50-fold improvement over the Meta’s Quest 2, which hits just 100 nits,” citing MIT Technology Review.

Nits are tricky to measure in a headset without the right equipment, and even then, they vary considerably from the center (usually the highest to the periphery).

The 5,000 nits cited by MIT Tech Review are the raw displays before the optics, whereas the nits for the MQ2 were those going to the eye. The AVP’s (and all other) pancake optics transmit about 11% (or less) of the light from an OLED in the center. With Pancake optics, there is the polarization of the OLED (>50% loss), a transmissive pass, and a reflective pass through a 50/50 mirror, which starts with at most 12.5% (50% cubed) before considering all the other losses from the optics. Then, there is the on-time-duty cycle of the AVP, which I have measured to be about 18.4%. VR devices want the on-time duty cycle to be low to reduce motion blur with the rapid motion of the head and 3-D game. The MQ3 only has a 10.3% on-time duty cycle (shorter duty cycles are easier with LED-illuminated LCDs). So, while the AVP display devices likely can emit about 5,000 nits, the nits reaching the eye are approximately 5,000 nits x 11% x 18.4% = 100 nits.

18:59 Computer Monitor Replacement is Rediculous

I wrote a three-part series on why I think monitor replacement by the Apple Vision Pro is ridiculous. Please see Apple Vision Pro (Part 5A) – Why Monitor Replacement is Ridiculous, Part 5B, and Part 5C. There are multiple fundamental problems that neither Apple nor anyone else is close to solving. The slide on the right summarizes some of the big issues.

Nyquist Sampling – Resampling Causes Blurring & Artifacts

I tried to explain the problem in two ways, one based on the frequency domain and the other on the spatial (pixel) domain.

19:29 Frequency Domain Discussion

Anyone familiar with signal processing may remember that a square wave has infinite odd harmonics. Images can be treated like 2-dimensional signals. A series of equally spaced, equal-width horizontal lines looks like a square wave in the vertical dimension. Thus, to represent them perfectly with a 3-D transform requires infinite resolution. Since the resolution of the AVP (or any VR headset) is limited, there will be artifacts such as blurring, wiggling, and scintillation.

As I pointed out in (Part 5A), computers tend to “cheat” and distort text and graphics to fit on the pixel grid and thus sidestep the Nyquist sampling problem that any VR headset must face when trying to make a 2-D image appear still in 3-D space. Those who know signal processing know that the Nyquist rate is 2x the highest frequency component. However, as noted above, horizontal lines have infinite frequency. Hence, some degradation is inevitable, but then we only have to beat the resolution limit of the eye, which, in effect, acts as a low-pass filter. Unfortunately, the AVP’s display is about 2-3x too low linearly (4-9x in two dimensions) in resolution for the artifacts not to be seen by a person with good vision.

22:15 Spatial Domain Discussion

To avoid relying on signal processing theory, in (Part 5A), I gave the example of how a single display pixel can be translated into 3-D space (right). The problem is that a pixel the size of a physical pixel in the headset will always cover parts of four physical pixels. Worse yet, with the slightest movement of a person’s head, how much of each pixel and even which pixels will be constantly changing, causing temporal artifacts such as wiggling and scintillation. The only way to reduce the temporal artifacts is to soften (low pass filter) the image in the resampling process.

23:19 Optics Distortion

In addition to the issues with representing a 2-D image in 3-D space, the AVP’s optics are highly distorting, as discussed in Apple Vision Pro’s (AVP) Image Quality Issues—First Impressions. The optical distortions can be “digitally corrected” but face the same resample issues discussed above.

25:51 Close-Up Center Crop and Foveated Boundary

The figures shown in this part of the video come from Apple Vision Pro’s (AVP) Image Quality Issues – First Impressions, and I will refer you to that article rather than repeat it here.

28:52 AVP’s Pancake Optics and Comparison to MQ3 and Birdbath

Much of this part of the video is covered in more detail in Apple Vision Pro’s (AVP) Image Quality Issues—First Impressions.

Using Eye Tracking for Optics Has Wider Implications

A key point made in the video is that the AVP’s optics are much more “aggressive” than Meta’s, and as a result, they appear to require dynamic eye tracking to work well. I referred to the AVP optics as being “unstable.” The AVP is constantly pre-correcting for distortion and color based on eye tracking. While the use of eye tracking for Foveated Rendering and control input is much discussed by Apple and others, using eye tracking to correct the optics has much more significant implications, which may be why the AVP has to be “locked” onto a person’s face.

Eye tracking for foveated rendering does not have to be nearly as precise as it is for correction, but using it for optical correction does. This leads me to speculate that the AVP requires the facial interfaces to lock the headset to the face, which is horrible regarding human factors, to support pre-correcting the optics. This follows my rule, “when smart people do something that appears dumb, it is because the alternative was worse.”

Comparison to (Nreal/Xreal) Birdbath

One part not discussed in the video or that article but shown in the associated figure (below) is the similarity of Pancake Optics are similar to Birdbath Optics. Nreal (now Xreal) Birdbath optics are discussed in my Nreal teardown series in Nreal Birdbath Overview.

Both pancake and birdbath optics start by polarizing the image from an OLED microdisplay. They use quarter waveplates to “switch” the polarization, causing it to bounce off a polarizer and then pass through it. They both use a 50/50 coated semi-mirror. They both use a combination of refractive (lens) and reflective (mirror) optics. In the case of the birdbath, the polarizer acts as a beam splitter to the OLED display so it does not block the view out, whereas with pancake optics, everything is inline.

31:34 AVP Color Uniformity Problem

The color uniformity and the fact that the color shift moves around with eye movement were discussed in Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3.

32:11 Comparing Resolution vs a Monitor

In Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3, I compared the resolution of the AVP (below left) to various computer monitors (below right) and the Meta Quest 3.

Below is a close-up crop of the center of the same image shown on the AVP, a 28″ monitor, and the Meta Quest 3. See the article for an in-depth explanation.

33:03 Vision OS 1.1 Change in MacBook mirror processing

I received and saw some comments about my Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3 that Vision OS 1.1 MacBook mirroring was sharper. I had just run a side-by-side comparison of displaying an image from a file on the AVP versus displaying the same image via mirroring a MacBook in Apple Vision Pro Displays the Same Image Differently Depending on the Application. So, I downloaded Vision OS 1.1 to the AVP and reran the same test, and I found a clear difference in the rendering of the MacBook mirroring (but not the display from the AVP file). However, it was not that the MacBook mirror image was shaper per se, but it was less bold. Even in the thumbnails below (click on them to see the full-size images). In the thumbnails below, note how the text looks less bold on the right side of the left image (OS 1.2) versus the right side of the right image.

Below are crops from the two images above, with the OS 1.1 image on the top and OS 1.0 on the bottom. The MacBook mirroring comes from the right sides of both images. Note how much bold the text and lines are in the OS 1.1 crop.

35:57 AVP Passthrough Cameras in the Wrong Location

38:43 AVP’s Optics are Soft/Blurry

As stated in Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3, the AVP optics are a little soft. According to Marquees Brownlee (see above) and others, my statement has caused controversy. I have heard others question my methods, but I have yet to see any evidence to the contrary.

I have provided my photographic evidence (right) and have seen it with my eyes by swapping headsets back and forth with high-resolution content. For comparison, the same image was displayed on the Meta Quest 3, and the MQ3 was clearly sharper. The “blur” on the AVP is similar to what one would see with a Gaussian blur with a radius of about 0.5 to 1 pixel.

Please don’t confuse “pixel resolution” with optical sharpness. The AVP has more pixels per degree, but the optics are a bit out of focus and, thus, a little blurry/soft. One theory is that it is being done to reduce the screen door effect (seeing the individual pixels) and make the images on the AVP look smoother.

The slight blurring of the AVP may reduce the screen door effect as the gap between pixels is thinner on the OLED displays than on the MQ3’s LCDs. But jaggies and scintillation are still very visible on the AVP.

41:41 Closing Discussion: “Did Apple Move the Needle?”

The video wraps up with Jason asking the open-ended question, “Did Apple Move the Needle?” I discuss whether it will replace a cell phone, home monitor(s), laptop on the road, or home TV. I think you can guess that I am more than skeptical that the AVP now or in the future will change things for more than a very small fraction of the people who use cell phones, laptops, and TVs. As I say about some conference demos, “Not everything that would make a great theme park experience is something you will ever want in your home to use regularly.”

Appendix: Rumor Mill’s 5,000 Nits Apple Vision Pro

When I searched the Internet to see if anyone had independently reported on the brightness of the AVP, I got the Google search answer in big, bold letters: “5,000 Nits” (right). Then, I went to the source of this answer, and it was none other than the MIT Technology Review. I then thought they must be quoting the display’s brightness, not the headset’s, but it reports that it is a “50-fold improvement over Meta Quest 2,” which is ridiculous.

I see this all the time when companies quote a spec for the display device, and it gets reported as the headset’s brightness/nits to the eye. The companies are a big part of the problem because most headset makers won’t give a number for the eye’s brightness in their specs. I should note that with almost all headset optics, the peak nits in the center will be much higher than those in the periphery. Through the years, one thing I have found that all companies exaggerate in their marketing is the brightness, either in lumens for projectors or nits for headsets.

An LCOS or DLP display engine can output over a million nits into a waveguide, but that number is so big (almost never given) that it is not confused with the nits to the eye. Nits are a function of light output (measured in Lumens) and the ability to collimate the light (a function of the size of the light source and illumination optics).

The “5,000 nits” source was a tweet by Ross Young of DSCC. Part of the Tweet/X thread is copied on the right. A few respondents understood this could not be the nits to the eye, and a few responders understood that it could not be to the eye. Responder BattleZxeVR even got the part about the duty cycle being a factor, but that didn’t stop many other later responders from getting it wrong.

Citing some other publications that didn’t seem to understand the difference between nits-in versus nits-out:

Quoting from The Daejeon Chronicles (June 2023): Apple Vision Pro Screens: 5,000 Nits of Wholesome HDR Goodness (with my bold emphasis):

Dagogo Altraide of ColdFusion has this to say about the device’s brightness capability:

“The screens have 5,000 nits of peak brightness, and that’s a lot. The Meta Quest 2, for example, maxes out at about 100 nits of brightness and Sony’s PS VR, about 265 nits. So, 5,000 nits is crazy. According to display analyst Ross Young, this 5,000 nits of peak brightness isn’t going to blind users, but rather provide superior contrast, brighter colors and better highlights than any of the other displays out there today.”

Quoting from Mac Rumors (May 2023): Apple’s AR/VR Headset Display Specs: 5000+ Nits Brightness for HDR, 1.41-Inch Diagonal Display and More:

With ~5000 nits brightness or more, the AR/VR headset from Apple would support HDR or high dynamic range content, which is not typical for current VR headsets on the market. The Meta Quest 2, for example, maxes out around 100 nits of brightness and it does not offer HDR, and the HoloLens 2 offers 500 nits brightness. Sony’s PSVR 2 headset has around 265 nits of brightness, and it does have an advertised HDR feature when connected to an HDR display.

The flatpanelshd (June 2023): Apple Vision Pro: Micro-OLEDs with 3800×3000 pixels & 90/96Hz – a paradigm shift did understand that the 5,000 nist was the display device and not to the eye:

DSCC has previously said that the micro-OLED displays deliver over 5000 nits of brightness but a good portion of that is typically lost due to the lenses and the display driving method.

As I wrote in Apple Vision Pro (Part 1) – What Apple Got Right Compared to The Meta Quest Pro, Snazzy Labs had an excellent explanation of the issues with the applications shown by Apple at the AVP announcement (it is a fun and informative video). But in another otherwise excellent video, What Reviewers Aren’t Telling You About Apple Vision Pro, I have to give him credit for recognizing that the MIT Tech Review had confabulated the display’s brightness with the headset’s brightness. But then hazarded a guess that it would be “after the optics, I bet it’s around 1,000 nits.” His guess was “just a bit outside” by about 10x. I do not want to pick on Snazzy Labs, as I love the videos I have seen from them, but I want to point out how much even technically knowledgeable people without a background in optics underestimate the light losses in headset optics.

Introduction

Hypervision, a company making a name for itself by developing very wide field of view VR pancake optics, just released a short article analyzing the Apple Vision Pro’s pancake on their website titled, First Insights about Apple Vision Pro Optics. I found the article very interesting from a company that designs pancake optics. I will give a few highlights and key points from Hypervision’s article, but I recommend going to their website for more information.

Hypervision has demonstrated a single pancake 140° VR and an innovative 240° dual pancake per eye optical design. I will briefly discuss Hypervision’s designs after the Apple Vision Pro optics information.

Apple Vision Pro’s Pancake Optical Design

Hypervision’s article starts with a brief description of the basics of pancake optics (this blog also discussed how pancake optics work as part of the article Meta (aka Facebook) Cambria Electrically Controllable LC Lens for VAC?).

Hypervision points out that an important difference in the Apple Pancake optics shown in the WWDC 2023 video and other pancake optics, such as the Meta Quest Pro, is that the Quarter Waveplate (QWP) retarder 2, as shown above, must be curved. Hypervision shows both Meta (Facebook) and Apple patent applications showing pancake optics with a curved QWP. Below are Figs 8 and 9 from Apple’s patent application and Hypervision’s translation into some solid optics.

Hypervision’s Field of View Analysis

Hypervision has also made a detailed field-of-view analysis. They discuss how VR experts who have seen the AVP say they think the AVP FOV is about 110°. Hypervision’s analysis suggests APV’s FOV “wishfully” could be as high as 120°. Either value is probably within the margin of error due to assumptions. Below is a set of diagrams from Hypervisions analysis.

Pixels Per Degree (ppd)

Hypervision’s analysis shows 34 pixels per Degree (ppd) on the lower end. The lower PPD comes from Hypervision’s slightly wider FOV calculations. Hypervision notes that this calculation is rough and may vary across the field of view as the optics may have some non-linear magnification.

I have roughly measured the Meta Quest Pro’s (MQP) ppd in the center and come up with about 22 ppd. Adjusting for about 1.8X more pixels linearly and the difference of 106 FOV for the MQP, and 110 for the AVP results, I get an estimate of about 39 ppd. Once again, with my estimate, there are a lot of assumptions. Considering everything, depending on the combination of high and low estimates, the AVP has between 34 ppd and 39 ppd.

Eye Box

Hypervision makes the point that due to using a smaller pixels size that thus requires more magnification, the eye box (and thus the sweet spot) of the AVP is likely to be smaller than some other headsets that use pancake optics with LCDs rather than the AVP’s use of Micro-OLEDs.

Hypervision

Hypervision clearly has some serious optical design knowledge. I first saw them in 2022, but as their optics have been aimed at VR, I have not previously written about them. But at AR/VR/MR 2023, they showed a vastly improved optical quality design using pancake optics to support 140° with a single pancake optics and 240° with what I call a dual pancake (per eye) design. I took more notice of pancake optics becoming all the rage in VR headsets with MR passthrough.

AR/VR/MR 2022 with Dual Fused Fresnel Lenses and 270°

I first saw Hypervision at AR/VR/MR in January 2022. At the time, they were demonstrating a 270° headset based on what I call a fused dual Fresnel optical design using two LCDs. I took some pictures (below), but I was not covering much about VR at the time unless it was related to passthrough mixed reality. While the field of view was very impressive, there were the usual problems with Fresnel optics and the seam between the dual Fresnel lenses was pretty evident.

AR/VR/MR 2023 Pancake Optics

Below are pictures I took at AR/VR/MR 2023 of Hypervision’s 140° single pancake and 240° dual pancake designs. The pancake designs were optically much better than their earlier Fresnel-based designs. The “seam” with the dual pancakes seemed barely noticeable (Brad Lynch also reported a barely invisible seam in his video). Hypervision has some serious optical design expertise.

I mentioned Brad Lynch of SadlyItsBradley and who covers VR in more detail about Hypervision. Brad had the chance to see them at Display Week 2023 and recorded a video discussing them. Brad said that multiple companies, including Lynx, were impressed by Hypervision.

Closing

Hypervision is a company with impressive optical design expertise, and they demonstrated that they understand pancake optics with their designs. I appreciate that they contacted me to let me know they had analyzed the Apple Vision Pro. It is one thing for me, with an MSEE who picked up some optics through my industry exposure, to try and figure out what is going on with a given optical design; it is something else to have the analysis from a company that has designed that type of optics. So once again, I would recommend reading the whole article on Hypervision’s site.