Introduction

The optics R&D  company Hypervision provided a detailed design analysis of the Apple Vision Pro’s optical design in June 2023 (see Apple Vision Pro (Part 4) – Hypervision Pancake Optics Analysis). Hypervision just released an interesting analysis exploring whether Micro-OLEDs, as used by the Apple Vision Pro, or LCDs used by Meta and most others, can support high 60 pixels per degree, angular resolution, and a wide FOV. Hypervision’s report is titled 60PPD: by fast LCD but not by micro OLED.

The optics R&D  company Hypervision provided a detailed design analysis of the Apple Vision Pro’s optical design in June 2023 (see Apple Vision Pro (Part 4) – Hypervision Pancake Optics Analysis). Hypervision just released an interesting analysis exploring whether Micro-OLEDs, as used by the Apple Vision Pro, or LCDs used by Meta and most others, can support high 60 pixels per degree, angular resolution, and a wide FOV. Hypervision’s report is titled 60PPD: by fast LCD but not by micro OLED. I’m going to touch on some highlights from Hypervision’s analysis. Please see their report for more details.

I Will Be at AWE Next Week

AWE is next week. I will be on the PANEL: Current State and Future Direction of AR Glasses at AWE on Wednesday, June 19th, from 11:30 AM to 12:25 PM. I still have a few time slots. If you want to meet, please email meet@kgontech.com.

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

An AWE speaker discount code – SPKR24D- provides a 20% discount. You can register for AWE here.

Apple Vision Pro Sharpness Study at AWE 2024 – Need Help

As Hypervision’s analysis finds, plus reports I have received from users, the Apple Vision Pro’s sharpness varies from unit to unit. AWE 2024 is an opportunity to sample many Apple Vision Pro headsets to see how the focus varies from unit to unit. I will be there with my high-resolution camera.

While not absolutely necessary, it would be helpful if you could download my test pattern, located here, and install it on your Apple Vision Pro. If you want to help, contact me via meet@kgontech.com or flag me down at the show. I will be spending most of my time on the Expo floor. If you participate, you can remain anonymous or receive a mention of you or your company at the end of a related article thanking you for your participation. I can’t promise anything, but I thought it would be worth trying.

AVP Burry Image Controversy

My article Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3 was the first to report that the AVP was a little blurry. I compared high-resolution pictures showing the same FOV with the AVP and the Meta Quest 3 (MQ3) in that article.

This article caused controversy and was discussed in many forums and influencers, including Linus Tech Tips and Marquess Brownlee (see Apple Vision Pro—Influencing the Influencers & “Information Density” and “Controversy” of the AVP Being a Little Blurry Discussed on Marques Brownlee’s Podcast and Hugo Barra’s Blog).

I have recently been taking pictures through Bigscreen Beyond’s (BSB) headset and decided to compare it with the same test (above right). In terms of optical sharpness, it is between the AVP and the MQ3. Interestingly, the BSB headset has a slightly lower angular resolution (~32 pixels per degree) than the AVP (~40 ppd) in the optically best part of the lens where these crops were taken. Yet, the text and line patterns look better on the BSB than AVP.

Hypervision’s Correction – The AVP is Not Out of Focus, and the Optics are Blurry

I speculated that the AVP seemed out of focus in Apple Vision Pro’s Optics Blurrier & Lower Contrast than Meta Quest 3. Hypervision corrected me that the softness could not be due to being out of focus. Hypervision has found that sharpness varies from one AVP to the next. The AVP’s best focus nominally occurs with an apparent focus of about 1 meter. Hypervision pointed out that if the headset’s device focus were slightly wrong, it would simply shift the apparent focus distance as the eye/camera would adjust to a small change in focus (unless it was so far off that eye/camera focusing was impossible). Thus, the blur is not a focus problem but rather a resolution problem with the optics.

Hypervision’s Analysis – Tolerances Required Beyond that of Today’s Plastic Optics

The AVP has very aggressive and complex pancake optics for a compact form factor while supporting a wide FOV with a relatively small Micro-OLED. Most other pancake optics have two elements, which mate with a flat surface for the polarizers and quarter waveplates that manipulate the polarized light to cause the light to pass through the optics twice (see Meta example below left). Apple has a more complex three-lens optic with curved polarizers and quarter waveplates (below right).

Based on my studies of how the AVP dynamically adjusts optical imperfections like chroma aberrations based on eye tracking, the AVP’s optics are “unstable” because, without dynamic correction, the imperfections would be seen as much worse.

Hypervision RMS Analysis

Hypervision did an RMS analysis comparing a larger LCD panel with a small Micro-OLED. It should probably come as no surprise that requiring about 1.8x (2.56/1.4) greater magnification makes everything more critical. The problem, as Hypervision points out, is that Micro-OLED on silicon can’t get bigger for many years due to semiconductor manufacturing limitations (reticle limit). Thus, the only way for Micro-OLED designs to support higher resolution and wider FOV is to make the pixels smaller and the optics much more difficult.

Hypervision Monte-Carlo Analysis

Hypervision then did a Monte-Carlo analysis factoring in optical tolerances. Remember, we are talking about fairly large plastic-molded lenses that must be reasonably priced, not something you would pay hundreds of dollars for in a large camera or microscope.

Hypervision’s 140 Degree FOV with 60PPD Approach

Hypervision believes that the only practical path to ~60PPD and ~140-degree FOV is with a 2.56″ LCD display. LCDs’ natural progression toward smaller pixels will enable higher resolution than their optics can support.

Conclusion

Overall, Hypervision makes a good case that current designs with Micro-OLED with pancake optics are already pushing the limits of reasonably priced optics. Using technology with somewhat bigger pixels makes resolving them easier, and having a bigger display makes supporting a wider FOV less challenging.

It might be that the AVP is slightly burry because it is already beyond the limits of a manufacturable design. So the natural question is, if AVP already has problems, how could they support higher resolution and wider FOV?

The size of Micro-OLEDs built on silicon backplanes is limited by a reticle limit of chip size of above ~1.4″ diagonally, at least without resorting to multiple reticle “stitching” (which is possible but not practical for a cost-effective device). Thus, for Micro-OLEDs to increase resolution, the pixels must be smaller, requiring even more magnification out of the optics. Then, increasing the FOV will require even more optical magnification of ever-tinier pixels.

LCDs have issues, particularly with black levels and contrast. Smaller illumination LEDs with local dimming may help, but they have not proven to work as well as micro-OLEDs.