A notice in my LinkedIn feed mentioned that Brilliant Labs has started shipping its new Frame AR glasses. I briefly met with Brilliant CEO Bobak Tavangar at AWE 2023 (right) and got a short demonstration of its “Monocle” prototype. So, I investigated what Brilliant Labs was doing with its new “Frame.”
This started as a very short article, but as I put it together, I thought it would be an interesting example of making design decisions and trade-offs. So it became longer. Looking at the Frames more closely, I found issues that concerned me. I don’t mean to pick on Brillant Labs here. Any hardware device like the Frames is a massive effort, and they talk like they are concerned about their customers; I am only pointing out the complexities of supporting AI with AR for a wide audience.
While looking at how the Frame glasses work, I came across some information related to the Apple Vision Pro’s brightness (in nits), discussed last time in Apple Vision Pro Discussion Video by Karl Guttag and Jason McDowall. In the same way, the Apple Vision Pro’s brightness is being misstated as “5000 nits,” and the Brilliant Labs Frame’s brightness has been misreported as 3,000 nits. In both cases, the nits are the “potential” out of the display and not “to the eye” after the optics.
I’m also repeating the announcement that I will be at SID’s DisplayWeek next week and AWE next month. If you want to meet, please email meet@kgontech.com.
DisplayWeek (next week) and AWE (next month)
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.
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 – Today as I post this). You can register for AWE here.
Brillian Labs Monocle and Frame used the same basic optical architecture, but it is better hidden in the Frame design. I will start with the Monocle, as it is easier to see the elements and the light path. I was a little surprised that both designs use a very simplistic, non-polarized 50/50 beam splitter with its drawbacks.
Below (left) is a picture of the Monocle with the light path (in green). The Monocle (and Frame) both use a non-polarizing 50/50 beamsplitter. The splitter projects 50% of the display’s light forward and 50% downward to the (mostly) spherical mirror, magnifying the image and moving the apparent focus. After reflecting from the mirror, the light is split again in half, and ~25% of the light goes to the eye. The front project image will be mirrored, with an unmagnified view of the display that will be fairly bright. Front projection or “eye glow” is generally considered undesirable in social situations and is something most companies try to reduce/eliminate in their optical designs.
The middle picture above shows a picture I took of the Monocle from the outside, and you can see the light from the beam splitter projecting forward. Figures 5A and 6 (above right) from Brilliant Labs’ patent application illustrate the construction of the optics. The Monocle is made with two solid optical parts, with the bottom part forming part of the beam splitter and the bottom surface being shaped to form the curved mirror and then mirror coated. An issue with the 2-piece Monocle construction is that the beam splitter and mirror are below eye level, which requires the user to look down to see the image or position the whole device higher, which results in the user looking through the mirror.
The Frame optics work identically in function, but the size and spacing differ. The optics are formed with three parts, which enables Brilliant to position the beam splitter and mirror nearer the center of the user’s line of sight. But as Brilliant Lab’s documentation shows (right), the new Frame glasses still have the virtual (apparent) image below the line of sight.
Having the image below the line of sight reduces the distortion/artifacts of the real world by looking through the beam splitter when looking forward, but it does not eliminate all issues. The top seam of the beam splitter will likely be visible as an out-of-focus line.
The image below shows part of the construction process from a Brilliant Labs YouTube video. Note that the two parts that form the beamsplitter with its 50/50 semi-mirror coating have already been assembled to form the “Top.”
As discussed in Nreal Teardown: Part 1, Clones and Birdbath Basics and its Appendix: Second Type of Birdbath, there are two types of “birdbaths” used in AR. The Birdbath comprises a curved mirror (or semi-mirror) and a beamsplitter. It is called a “birdbath” because the light reflects out of the mirror. The beamsplitter can be polarized or unpolarized (more on this later). Birdbath elements are often buried in the design, such as the Lumus optical design (below left) with its curved mirror and beam splitter.
From 2023 AR/VR/MR Lumus Paper – A “birdbath” is one element of the optics
Many AR glasses today use the birdbath to change the focus and act as the combiner. The most common of these designs is where the user looks through a 50/50 birdbath mirror to see the real world (see Nreal/Xreal example below right). In this design, a polarised beam splitter is usually used with a quarter waveplate to “switch” the polarization after the reflection from the curved semi-mirror to cause the light to go through the beam splitter on its second pass (see Nreal Teardown: Part 1, Clones and Birdbath Basics for a more detailed explanation). This design is what I refer to as a “Look through the mirror” type of birdbath.
Brilliant Labs uses a “Look through the Beamsplitter” type of birdbath. Google Glass is perhaps the most famous product with this birdbath type (below left). This birdbath type has appeared in Samsung patents that were much discussed in the electronic trade press in 2019 (see my 2019 Samsung AR Design Patent—What’s Inside).
LCOS maker Raontech started showing a look through the beamsplitter reference design in 2018 (below right). The various segments of their optics are labeled below. This design uses a polarizing beam splitter and a quarter waveplate.
If you look at the RaonTech or Google Glass splitter, you should see that the beam splitter is the full height of the optics. However, in the case of the Frames and Monocle designs (right), the top and bottom beam splitter seams, the 50/50 mirror coating, and the curved mirror are in the middle of the optics and will be visible as out-of-focus blurs to the user.
Pros and Cons of Look-Through-Mirror versus Look-Through-Beamsplitter
The look-through-mirrorbirdbaths typically use a thin flat/plate beam splitter, and the curved semi-mirror is also thin and “encased in air.” This results in them being relatively light and inexpensive. They also don’t have to deal with the “birefringence” (polarization changing) issues associated with thick optical materials (particularly plastic). The big disadvantage of the look-through-mirror approach is that to see the real world, the user must look through both the beamsplitter and the 50/50 mirror; thus, the real world is dimmed by at least 75%.
The look-through-beamsplitter designs encase the entire design in either glass or plastic, with multiple glued-together surfaces coated or coated with films. The need to encase the design in a solid means the designs tend to be thicker and more expensive. Worse yet, typical injected mold plastics are birefringent and can’t be used with polarized optics (beamsplitters and quartwaveplates). Either heavy glass or higher-cost resin-molded plastics must be used with polarized elements. Supporting a wider FOV becomes increasingly difficult as a linear change in FOV results in a cubic increase in the volume of material (either plastic or glass) and,thus, the weight. Bigger optics are also more expensive to make. There are also optical problems when looking through very thick solid optics. You can see in the Raontech design above how thick the optics get to support a ~50-degree FOV. This approach “only” requires the user to look through the beam splitter, and thus the view of the real world is dimmed by 50% (or twice as much light gets through as the look-through-mirror method).
Pros and Cons Polarized Beam Splitter Birdbaths
Most companies with look-through-mirror and look-through-beamsplitter designs, but not Brilliant Labs, have gone with polarizing beam splitters and then use quarter waveplates to “switch” the polarization when the light reflects off the mirror. Either method requires the display’s light to make a reflective and transmissive pass via the beam splitter. With a non-polarized 50/50 beam splitter, this means multiplicative 50% losses or only 25% of the light getting through. With a polarized beam splitter, once the light is polarized with a 50% loss, with proper use of quarter waveplates, there are no more significant losses with the polarized beamsplitter.
Another advantage of the polarized optics approach is that front-projection can be mostly eliminated (there will be only a little due to scatter). The look-through-mirror method can be accomplished (as discussed in Nreal Teardown: Part 1, Clones and Birdbath Basics) with a second-quarter waveplate and a front polarizer. With the look-through-beamsplitter method, a polarizer before the beamsplitter will block the light that would project forward off the polarized beamsplitter.
As mentioned earlier, using polarized optics becomes much more difficult with the thicker solid optics associated with the look-through-beamsplitter method.
Brilliant Labs Frame Design Decision Options
It seems that at every turn in the decision process for the Frame and Monocle optics, Brilliant Labs chose the simplest and most economical design possible. By not using polarized optics, they gave up brightness and will have significant front projection. Still, they can use much less expensive injection-molded plastic optics that do not require polarizers and quart waveplates. They avoided using more expensive waveguides, which would be thinner but require LCOS or MicroLED (inorganic LED) projection engines, which may be heavier and larger. Although, the latest LCOS and MicroLED engines are getting to be pretty small and light, particularly for a >30-degree FOV (see DigiLens, Lumus, Vuzix, Oppo, & Avegant Optical AR (CES & AR/VR/MR 2023 Pt. 8)).
Frames Brightness to the Eye – Likely >25% of 3,000 nits – Same Problem as Apple Vision Pro Reporting
As discussed in the last article on the Apple Vision Pro (AVP) in the Appendix: Rumor Mill’s 5,000 Nits Apple Vision Pro, reporters/authors constantly make erroneous comparisons of “display-out nits” with one device and to the nits-to-the-eye of other devices. Also, as stated last time, the companies appear to want this confusion by avoiding specifying the nits to the eye as they benefit from reporters and others using display device values.
I could not find an official Brilliant Labs value anywhere, but it seems to have told reporters that “the display is 3,000 nits,” which may not be a lie, but it is misleading. Most articles will dutifully give the “display number” but fail to say that they are “display device nits” and not what the user will see and leave it to the readers to make the mistake, while other reporters will make the error themselves.
The display on Frame is monocular, meaning the text and graphics are displayed over the right eye only. It’s fairly bright (3,000 nits), though, so readability should be good even outdoors in sunlit areas.
As with the Brilliant Labs Monocle – the clip-on, open-source device that came before Frame – information is displayed in just one eye, with overlays being pumped out at around 3,000 nits brightness.
Android Central in androidcentral’s These AI glasses are being backed by the Pokemon Go CEO, who was at least making it clear that it was the display device numbers, but I still think most readers wouldn’t know what to do with this number. They added the tidbit that the panels were made by Sony, and they discussed pulse with modulation (also known as duty cycle). Interestingly, they talk about a short on-time duty cycle causing problems for people sensitive to flicker. In contrast, VR game fans favor a very short on-time duty cycle, what Brad Lynch of SadlyItsBradly refers to as low-persistence) to reduce blurring.
A 0.23-inch Sony MicroOLED display can be found inside one of the lenses, emitting 3,000 nits of brightness. Brilliant Labs tells me it doesn’t use PWM dimming on the display, either, meaning PWM-sensitive folks should have no trouble using it.
Below is a summary of Sony OLED Microdisplays aimed at the AR and VR market. On it, the 0.23 type device is listed with a max lumence of 3,000 nits. However, from the earlier analysis, we know that at most 25% of the light can get through Brilliant Labs Frame birdbath optics or at most 750 nits (likely less due to other optical losses). This number assumes that the device is driven at full brightness and that Brilliant Labs is not buying derated devices at a lower price.
I can’t blame Brilliant Labs because almost every company does the same in terms of hiding the ball on to-the-eye brightness. Only companies with comparatively high nits-to-the-eye values (such as Lumus) publish this spec.
Sony Specifications related to the Apple Vision Pro
The Sony specifications list a 3.5K by 4 K device. The industry common understanding is that Apple designed a custom backplane for the AVP but then used Sony’s OLED process. Notice the spec of 1,000 cd/m2 (candelas per meter squared = nits) at a 20% duty ratio. While favorable for VR gamers wanting less motion blur, the low on-duty cycle time is also a lifetime issue. The display device probably can’t handle the heat from being driven for a high percentage of the time.
It would be reasonable to assume that Apple is similarly restricted to about a 20% on-duty cycle. As I reported last time in the Apple Vision Pro Discussion Video by Karl Guttag and Jason McDowall, I have measured the on-duty cycle of the AVP to be about 18.4% or close to Sony’s 20% for their own device.
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.
View Into the Frame Glasses
I don’t want to say that Brilliant Labs is doing anything wrong or that other companies don’t often do the same. Companies often take pictures and videos of new products using non-functional prototypes because the working versions aren’t ready when shooting or because they look better on camera. Still, I want to point out something I noticed with the pictures of the CEO, Bobak Tavangar (right), that was published in many of the articles in the Frames glasses. I didn’t see the curved mirror and the 50/50 beam splitter.
In a high-resolution version of the picture, I could see the split in the optics (below left) but not the darkened rectangle of the 50/50 mirror. So far, I have found only one picture of someone wearing the Frame glasses from Bobak Tavangar’s post on X. It is of a person wearing what appears to be a functional Frame in a clear prototype body (below right). In the dotted line box, you can see the dark rectangle from the 50/50 mirror and a glint from the bottom curved mirror.
I don’t think Brilliant Labs is trying to hide anything, as I can find several pictures that appear to be functional frames, such as the picture from another Tavangar post on X showing trays full of Frame devices being produced (right) or the Forbes picture (earlier in the Optical section).
What was I hoping to show?
I’m trying to show what the Frame looks like when worn to get an idea of the social impact of wearing the glasses. I was looking for a video of someone wearing them with the Frame turned on, but unfortunately, none have surfaced. From the design analysis above, I know they will project a small but bright image view with a mirror image of the display off of the 50/50 mirror, but I have not found an image showing the working device from the outside looking in.
Exploded View of the Frame Glasses
The figure below is taken from Brilliant Lab’s online manual for the Frame glasses (I edited it to reduce space and inverted the image to make it easier to view). By AR glasses standards, the Frame design is about as simple as possible. The choice of two nose bridge inserts is not shown in the figure below.
There is only one size of glasses, which Brilliant Labs described in their AMA as being between a “medium and large” type frame. They say that the temples are flexible to accommodate many head widths. Because the Frames are monocular, IPD is not the problem it would be with a biocular headset.
AddOptics is making custom prescription lenses for the Frames glasses
Bonding to the Frames will make for a cleaner and more compact solution than the more common insert solution, but it will likely be permanent and thus a problem for people whose prescriptions change. In their YouTube AMA, Brilliant Labs said they are working with AddOptics to increase the range of prescription values and support for astigmatism.
They didn’t say anything about bifocal or progressive lens support, which is even more complicated (and may require post-mold grinding). As the virtual image is below the centerline of vision, it would typically be where bifocal and progressive lenses would be designed for reading distance (near vision). In contrast, most AR and VR glasses aim to put the virtual image at 2 meters, considered “far vision.”
The Frame’s basic specs
Below, I have collected the basic specs on the Frame glasses and added my estimate for the nits to the eye. Also shown below is their somewhat comical charging adapter (“Mister Charger”). None of these specs are out of the ordinary and are generally at the low end for the display and camera.
Monocular 640×400 resolution OLED Microdisplay
~750nits to the eye (based on reports of a 3,000 Sony Micro-OLED display device)
(90% on-time duty cycle using an
20-Degree FOV
Weight ~40 grams
1280×720 camera
Microphone
6 axis IMU
Battery 222mAh (plus 149mAh top-up from charging adapter)
With 80mA typical power consumption when operating 0.580 on standby)
CPU nRF52840 Cortex M4F (Nordic ARM)
Bluetooth 5.3
Everything in AR Today is “AI”
Brilliant Labs is marketing the frames as “AI Glasses.” The “AI” comes from Brilliant Lab’s Noa ChatGPT client application running on a smartphone. Brillant Labs says the hardware is “open source” and can be used by other companies’ applications.
I’m assuming the “AI” primarily runs on the Noa cell phone application, which then connects to the cloud for the heavy-lifting AI. According to their video by Brillant Labs, while on the Monocle, the CPU only controls the display and peripherals, they plan to move some processing onto the Frame’s more capable CPU. Like other “AI” wearables, I expect simple questions will get immediate responses while complex questions will wait on the cloud.
Conclusions
To be fair, designing glasses and wearable AR products for the mass market is difficult. I didn’t intend to pick on Brilliant Lab’s Frames; instead, I am using it as an example.
With a monocular, 20-degree FOV below the center of the person’s view, the Frames are a “data snacking” type AR device. It is going to be competing with products like the Human AI projector (which is a joke — see: Humane AI – Pico Laser Projection – $230M AI Twist on an Old Scam), the Rabbit R1, Meta’s (display-less) Ray Ban Wayfarer, other “AI” audio glasses, and many AR-AI glasses similar to the Frame that are in development.
This blog normally concentrates on display and optics, and on this score, the Frame’s optics are a “minimal effort” to support low cost and weight. As such, they have a lot of problems, including:
Small 20-degree FOV that is set below the eyes and not centered (unless you are lucky with the right IPD)
Due to the way the beam 50/50 splitter cuts through the optics, it will have a visible seam. I don’t think this will be pleasant to look through when the display is off (but I have not tried them yet). You could argue that you only put them on “when you need them,” but that negates most use cases.
The support for vision correction appears to lock the glasses to a single (current) prescription.
Regardless of flexibility, the single-size frame will make the glasses unwearable for many people.
The brightness to the eye of probably less than 750 nits is not bright enough for general outdoor use in daylight. It might be marginal if used combined with clip-on sunglasses or if they are used in the shade.
As a consumer, I hate the charger adapter concept. Why they couldn’t just put a USB-C connector on the glasses is beyond me and a friction point for every user. Users typically have dozens of USB-C power cables today, but your device is dead if you forget or lose the adaptor. Since these are supposed to be prescription glasses, the idea of needing to take them off to charge them is also problematic.
While I can see the future use model for AI prescription glasses, I think a display, even one with a small FOV, will add significant value. I think Brillant Labs’s Frames are for early adopters who will accept many faults and difficulties. At least they are reasonably priced at $349, by today’s standards, and don’t require a subscription for basic services without too many complex AI queries requiring the cloud.
In part 1, I wrote that I was planning on covering optics and display companies at CES and the SPIE AR/VR/MR conferences in 2024 in part 2 of the video I made with Jason McDowall in this article. However, as I started filling in extra information on the various companies, the article was getting long, so I broke the optics and displays into two separate articles.
In addition to optics companies, I will also be touching on eye track with Tobii, who is doing both optics and eye tracking, and Zinn Labs.
Subscription Options Coming to KGOnTech
Many companies, including other news outlets and individuals, benefit from this blog indirectly through education or directly via the exposure it gives to large and small companies. Many, if not most, MR industry insiders read this blog worldwide based on my conference interactions. I want to keep the main blog free and not filled with advertising while still reporting on large and small companies. To make financial sense of all this and pay some people to help me, I’m in the process of setting up subscription services for companies and planning on (paid) webinars for individuals. If you or your company might be interested, please email subscriptions@kgontech.com.
Outline of the Video and Additional Information
Below is an outline of the second hour of the video, as well as additional comments and links to more information. The times in blue on the left of each subsection below link to the time in the YouTube video discussing a given company.
Schott AG is one of the world’s biggest makers of precision glass. In 2020, Schott entered into a strategic partnership with Lumus, and at AR/VR/MR 2024 and 2023, Lumus was prominently featured in the Schott booth. While Schott also makes the glass for diffractive waveguides, the diffraction gratings are usually left to another company. In the case of the Lumus Reflective waveguides, Schott makes the glass and has developed high-volume waveguide manufacturing processes.
Lumus waveguides consistently have significantly higher optical efficiency (for a given FOV), better color uniformity, better transparency, higher resolution, and less front projection (“eye glow”) than any diffractive waveguide. Originally, Lumus had 1-D pupil-expanding waveguides, whereas diffractive waveguides were 2-D pupil-expanding. The 1-D expanding waveguides required a large projection engine in the non-expanding direction, thus making the projection optics bigger and heavier. In 2021, Lumus first demonstrated their 2-D expanding Maximus prototype waveguides with excellent image quality, 2K by 2K resolution, and 50° FOV. With 2-D expansion, projection image optics could be much smaller. Lumus has continued to advance its Reflective 2D expanding waveguide technology with the “Z-Lens.” Lumus says that variants of this technology could support more than a 70-degree FOV.
Waveguides depend on “total internal reflection” (TIR). For this TIR to work, diffractive waveguides and earlier Lumus waveguides require an “air gap” between the waveguide surface and any other surfaces, including “push-pull” lenses, for moving the waveguide’s apparent focus distance and vision correction. These air gaps can be hard to maintain and source unwanted reflections. Lumus Z-Lens can be embedded in optics with no air gap (and the first waveguide to make this claim) due to the shallower angles of the TIR reflections.
While Lumus waveguides are better than any diffractive waveguide in almost every image quality and performance metric, their big questions have always revolved around volume manufacturing and cost. Schott thinks that the Lumus waveguides can be manufactured in high volume at a reasonable cost.
Over the last ten years, I have seen significant improvements in almost every aspect of diffractive waveguides from many companies (for example, my articles on DigiLens and Dispelix). Diffractive waveguides are easier, less expensive, and much easier to customize. Multiple companies have diffraction waveguide design tools, and there are multiple fabrication companies.
As I point out in the video, many MR applications don’t need the highest image quality or resolution; they need “good enough” for the application. Many MR applications only need simple graphics and small amounts of text. Many applications only require limited colors, such as red=bad, green=good, yellow=caution, and white or cyan for everything else. While others can get away with monochrome (say green-only). For example, many military displays, including night vision, are often monochrome (green or white), and most aviation HUDs are green-only.
I often say there is a difference between being “paid to use” and ” paying for” a headset. By this, I mean that someone is paid to use the headset to help them be more effective in their job, whereas a consumer would be paying for the headset.
Fourier is developing metasurface technology to reflect and redirect light from a projector in the temple area of AR glasses to the eye. If a simple mirror-type coating were placed on the lens, projected light from the temple would bounce off at an angle that would miss the eye.
Fourier’s metasurface (and HOEs) can act not only as a tilted flat mirror but also as a tilted curved mirror with “optical power” to change magnification and focus. At least in theory (I have not seen it, and Fourier is still in development), the single metasurface would be simpler, compact, and have better optical efficiency than birdbath optics (e.g., Xreal and many others) and lower cost and with much better optical efficiency than waveguides. But while the potential benefits are large, I have yet to see a HOE (or metasurface) with great image quality. Will there, for example, be color uniformity, stray light capture, and front projection (“eye glow”) issues as seen with diffractive waveguides?
Laser beam scanning with direct temple projection, such as North Focals (see below left), uses a Hologram embedded or on the surface of a lens to redirect the light. This has been a common configuration for the lower resolution, small FOV, and very small eyebox Laser Beam Scanning (LBS) glasses shown by many companies, including North, Intel, and Bosch. Alternatively, LCOS, DLP, MicroLED, and laser beam scanning projectors have used waveguides to redirect the light and increase the eyebox size (the eyebox is the range of movement of the eye relative to the glasses where the whole image can be seen).
Avegant (above right), Lumus, Vuzix, Digilens, Oppo, and many others have demonstrated that with waveguides with DLP, LCOS, and MicroLEDs in very small form factors as HOEs and Metasufaces (see DigiLens, Lumus, Vuzix, Oppo, & Avegant Optical AR (CES & AR/VR/MR 2023 Pt. 8). Still, waveguides are much lower in efficiency, so much so that the use of MicroOLED is impractical with waveguides. In contrast, using MicroOLED displays is possible with HOEs and Fourier’s metalenses. There are also potential differences in how prescription lenses could be supported.
As discussed above, holographic mirrors can also be used to form the equivalent of a curved mirror that is also tilted. The large CREAL3D prototype (below left) shows the two spherical semi-mirrors. CREAL3D planes to replace these physical mirrors with a flat HOE (below right).
Fourier metalens would perform the same optical function as the HOE. We will have to wait and see the image quality and whether there are significant drawbacks with either HOEs or metalenses. My expectation is that both metalenses and HOEs will have similar issues as diffraction gratings.
Some related articles and videos on small form factor optics and Videos.
Morphontonics has developed methods for making waveguides and similar diffractive structures on large sheets of glass. They can make many small diffractive waveguides at a time or fewer large optical devices. In addition to waveguides, Morphotonics makes a light guide structure for the Leia Lightfield monitor and tablet.
Cellid is a relatively new entrant in waveguide making. I have seen their devices for several years. As discussed in the video, Cellid has been continually improving its waveguides. However, at least at present, it still seems to be behind the leading diffractive waveguide companies in terms of color uniformity, FOV, and front projection (“eye glow).
Several companies are using LetinAR’s PinTilt optics in the AR glasses. At CES, JorJin was showing their J8L prototypes in the LetinAR booth. Nimo (as discussed in Mixed Reality at CES and the AR/VR/MR 2024 Video (Part 1 – Headset Companies) was showing their LentinAR-based glasses in their own booth. Sharp featured their LentinAR glasses in their booth but didn’t mention they were based on LetinAR optics.
LetinAR originally developed “pin mirror” optics, which I first covered in 2018 (see CES 2018 in the listings below). The pin-mirror technology has evolved into their current “PinTilt” technology.
While LetinAR has several variations of the PinTilt, the “B-Type” (right) is the one I see being used. They use an OLED microdisplay as the display device. The image light from the OLED makes a TIR (total internal reflection) bounce off the outside surface into a collimating/focusing mirror and then back up through a series of pupil-replicating slats. The pupil replication slats enable the eye to move around and support a larger FOV.
As I discussed in the video, the image quality is much better than with the Pin-Mirrors, but gaps can be seen if your eye is not perfectly placed relative to the slats. Additionally, with the display off, the view can be slightly distorted, which can likely be improved in the manufacturing process. LetinAR also let me know that they are working on other improvements.
LetinAR’s PinTilt is much more optically efficient than diffractive or even Lumus-type reflective waveguides, as evidenced by its use of micro-OLEDs rather than much brighter LCOS, DLP, or micro-LEDs. At the same time, they offer a form factor that is close to waveguides.
Tooz was originally spun out of Zeiss Group in 2018, but in March 2023, they returned to become part of Zeiss. Zeiss is an optical giant founded in 1846 but is probably most famous to Americans as the company making the inserts for the Apple Vision Pro.
Tooz’s “Curved Waveguide” works differently than diffractive and Lumus-type reflective waveguides, which require the image to be collimated, use many more TIR light bounces, and have pupil replication. Strictly speaking, none of these are”waveguides,” but the diffractive and Lumus-type devices are what most people in the industry call waveguides.
The Tooz device molds optics and a focusing mirror to move the focus of the display device, which currently can be either a Micro-OLED or, more recently, (green only) Micro-LED. The image light then makes a few TIR bounces before hitting a Fresnel semi-mirror, which directs the light toward the user’s eye (above right). The location of the Fresnel semi-mirror, and thus the image, is not centered in the user’s field of view but slightly off to one side. It is made for a monocular (single-eye) display. The FOV is relatively small with 11- and 15-degree designs.
Tooz’s Curved Waveguide is aimed at data snacking. It has a small FOV and a Monocular display off the side. The company emphasizes the integration of prescription optics and the small and lightweight design, which is optically much more efficient than other waveguides.
Tooz jointly announced just before the AR/VR/MR conference that they were working with North Ocean Photonics to develop push-pull optics to go with waveguides. Tooz, in their AR/VR/MR 2024 presentation, discussed how they were trying to be the prescription optics provider for both their curved waveguides and what they call planar waveguides. One of their slides demonstrated the thickness issue with putting a push/pull set of lenses around a flat waveguide. The lenses need to be thicker to “inscribe” the waveguide due to their curvature (below right).
Oorym is a small startup founded by Yaakov Amitai, a founder and former CTO of Lumus. Oorym has a “waveguide” with many more TIR bounces than Tooz’s design but many less than diffractive and Lumus waveguides. They use a Fresnel light redirecting element. It does not require collimated light and is much more efficient than other waveguides. They can support more than a 50-degree FOV. It is thicker and more diffractive, and Lumus waveguides are in the same order as the thickness of LetinAR. Oorym is also developing a non-head-mounted Heads-Up Display (HUD) device.
Gixel’s technology has to be among the most “different” I have seen in a long time. The concept is to have a MicroLED “bar” display with only a single or a few rows of pixels in one direction and with the full horizontal resolution in the other. The “rows” may have full-color pixels or a series of 3 single-color row arrays. Then, a series of pupil-replicating slats rotate to scan the bar/row image vertically synchronously with a time-sequential change of the row display. In this way, the slats scan row display forms a whole image to the eye (and combines the colors if there are separate displays for each color).
They didn’t have a full working prototype, but they did have the rotating slats working.
My first impression is that it has a Steampunk feel to the design. I can see a lot of issues with the rotating slats, their speed and vibration, the time-sequential display, and a mirage of other potential issues. But still, it wins for the sheer audacity of the approach.
23:42 Meta Research (Time Sequential Fixed Foveated Display) & Varjo
From 2017 Article of Varjo
Meta Research presented the concept of a time-sequence fixed-foveated display using single pancake optics. The basic idea is that pancake optics work by making two passes through some of the refractive and mirror optics, which magnifies the display. In a normal pancake, quarter waveplates change the light’s polarization and affect the two passes. A (pixel-less) liquid crystal shutter can act as a switchable quarter waveplate. This way, the display light will make one or two passes through part of the optics to cause two different magnifications. By time sequencing the display with the LC shutter’s switching, both a lower angular resolution but larger image and a higher angular resolution but smaller “foveated” display will be seen by the eye time sequentially.
This basically happens with a single set of optics and a single display, which is what Varjo was doing with their “fixed foveated display,” which used two display devices, optics, and a combining beam splitter.
I like to warn people that when a research group from a big company presents a concept like this to all their competitors at a conference like AR/VR/MR, it is definitely NOT what they are doing in a product.
Fixed (and Eye Tracking) Foveated Displays
In 2017, Varjo was focused on its foveated display technology. Their first prototype had a “fixed foveated display,” meaning the central high-resolution region didn’t move. Varjo claimed they would soon have the foveated display tracking the eye, but as far as I know, they never solved the problem.
It turns out that tracking the eye and moving the display is a seemingly impossible problem to solve with the eye’s saccadic movement, even with exceptional eye tracking. As I like to say, “While eye tracking may know where the eye is pointing, you don’t know what the eye has seen.” Originally, researchers thought that human vision fully blanks with saccadic movement, but later research suggests that it only semi-blanks out vision with movement. Combined with the fact that what a human “sees” is basically a composite of multiple eye positions, making a foveated display that tracks the eye is exceedingly difficult, if not impossible. The problem with artifacts due to eye movement, such as field sequential color breakup, they will tend to appear as flashes that are distracting.
We are seven years since Varjo told me they were close to solving the eye-tracking foveated display. Varjo figured out that about 90% of the benefit of a moving foveated display could be realized with a fixed foveated display near the center of the FOV. They may also have realized that solving the problems with a moving foveated display was more difficult than they thought. Regardless, Varjo has pivoted from being a “foveated display company” to a “high-resolution VR/MR company” aimed primarily at enterprise applications. Pixel sizes and resolution of display devices improved to the point where it is now better to use a higher resolution display than to combine two displays optically.
Eyeway Vision Foveated Display (and Meta)
In 2021, I visited Eyeway Vision, which also worked on foveated displays using dual laser scanning displays per eye. After an acquisition by Meta fell through, Eyeway Vision went bankrupt. Eyeway Vision had a fixed foveated display and sophisticated eye tracking, but it went bankrupt before solving the moving foveated display.
Eyeway Vision’s founder, Boris Greenburg, has recently joined VoxelSensors, and VoxelSensors is looking at using their technology for eye/gaze tracking and SLAM (see Zinn Labs later)
Foveated Display (ex., Varjo) vs. Foveated Rending (ex., Apple Vision Pro)
I want to be clear between foveated rendering, where the display is fixed, and just the level of detail in the rendering changes based on eye tracking, from a foveated display, where a high-resolution sub-display is inset within a lower resolution display. Foveated rendering such as the Apple Vision Pro or Meta Quest Pro is possible, although today’s implementations have problems. However, it may be impossible to have a successful eye-tracking foveated display.
For more on this blog’s coverage of Foveated Displays, see:
At AR/VR/MR 2024, Magic Leap gave a presentation that mostly discussed human factors. They discussed some issues they encountered when developing the Magic Leap One, including fitting a headset to a range of human faces (below right). I thought the presentation should have been titled “Why the Apple Vision Pro is having so many problems with fitting.”
In 2016, This Blog Caught Magic Leap’s Misleading Video
In showing Magic Leap’s history, they showed a prototype headset that used birdbath optics (above left). Back in 2016, Magic Leap released a video that stated, “Shot directly through Magic Leap technology . . . without the use of special effects or compositing.” I noted at the time that this left a lot of legal wiggle room and that it might not be the same “technology” they would use in the final product, and this turned out to be the case. I surmised that the video used OLED technology. It’s also clear from the video that it was not shot through a waveguide. It appears likely that the video was shot using an OLED through birdbath optics, not with the Waveguide Optics and LCOS display that the Magic Leap One eventually used.
In 2019, Magic Leap sued (and lost to) Nreal (now Xreal), which developed an AR headset using birdbath optics and an OLED display. Below are links to the 2016 article analyzing the Magic Leap deceptive video and my 2020 follow-up article:
Sorry for being so blunt, but NewSight Reality’s “transparent” MicroLED concept does not and will not ever work. The basic concept is to put optics over small arrays of LEDs, and similar to pupil replication, the person will see an image. It is the same “physics” as MojoVision’s contact display (which I consider a scam). In fact, NewSight’s prototype has nine MojoVision displays on a substrate (below center)
The fundamental problem is that to get a display of any resolution, plus the optics, the “little dots” are so big that they, combined with diffraction, cause a blurry set of gray dots in a person’s vision. Additionally, the pupil replication effect ends up with a series of circles where you can see the image.
I covered AddOptics last year in CES 2023 (Part 3)—AddOptics Custom Optics. The big addition in 2024 was that they showed their ability to make push-pull optics for sandwiching a waveguide. They showed they could support waveguides that required an air gap or not. As far as I am aware, most, if not all, diffractive waveguides require an air gap. The only waveguide I know of that claims they don’t need an air gap is the newer Lumus reflective-based waveguide (discussed in a previous article). Still, I have not heard of whether AddOptics is working with Lumus or one of Lumus’s customers.
Luxexcel had developed a process to directly 3-D print optics without the need for any resurfacing. This means they need to print very fine layers very precisely, lens by lens. While it means each lens it custom can be custom fit, it also seems to be an expensive process compared to the way prescription lenses are made today. By making “low run” 3-D printed molds (something that Luxexcel could also do), AddOptics would have a lower cost per unit and a faster approach. It would require having a stock of molds, but it would not require a prohibitive number of molds to support most combinations of diopter and cylinder (astigmatism) correction.
Tobii, founded in 2001, has long been known for its eye-tracking technology. Tobii was looking to embed LED illuminators in lenses and was working with Interglass. When Interglass (founded in 2004) went bankrupt in 2020, Tobii hired the key technical team members from Integlass. Meta Materials (not to be confused with Meta, formerly Facebook) acquired the assets of Interglass and is also making a similar technology.
The Interglass/Tobii/Meta-Materials process uses many glass molds to support variations of diopter and cylinder adjustments for prescriptions. The glass molds are injected with UV-cured plastic resin, which, after curing, forms lens blanks/rounds. When molding, the molds can be rotated to set the cylinder angle. The round lens blanks can then be cut by conventional lens fitting equipment.
At 2023’s AR/VR/MR, Tobii demonstrated (left two pictures below) how their lenses were non-birefringent, which is important when working with polarized light-based optics (e.g., Pancake Optics, which Tobii says they can make) and displays (LCDs and LCOS). Tobii has videos on its website that show the lens-making and electronic integrating process (below right).
Zinn Labs uses a Prophesee event-based camera sensor (Zinn and Prophesee announcement). The Prophesee event camera sensor was jointly developed with Sony. Zinn uses Prophesee’s 320×320 6.3μm pixel BSI (BackSide Illuminated) event-based sensor in a 1/5” optical format.
Event camera pixels work like the human eye in detecting changes rather than the absolute value of each pixel. The pixels are much more complex than a conventional camera sensor, with photodiodes and comparators integrated into each pixel using Sony’s BSI process. Rather than scanning out the pixel value at a frame rate, each pixel reports when it changes significantly (more details can be found in the Prophesee white paper – free, but you have to give an email address). The advantage of the event camera in image recognition is that it tends to filter out/ignore everything that is not changing.
Zinn Labs has developed algorithms that then take the output from the event camera and turn it into where the eye is gazing (for more information, see here).
VoxelSensors (and Zinn Labs)
VoxelSensors has a very different type of event sensor called a “SPAES (Single Photon Active Event Sensor)” that could be used for eye/gaze tracking. Quoting from VoxelSensors:
VoxelSensors leverages its distinctive SPAES (Single Photon Active Event Sensor) technology, allowing the integration of multimodal perception sensors, such as innovative hand and gaze tracking and SLAM, with high precision, low power consumption, and low latency. Fusing these key modalities will enable the development of next-gen XR systems.
VoxelSensors’s SPAES uses a laser scanner to scan the area of interest in a narrow-band infrared laser (where the Prophesee event camera would use IR LED flood illumination) and then detect the laser scanner’s return to the area of interest. With narrow-band filtering to filter out all but the laser’s wavelength, the SPAES is designed to be extremely sensitive (they claim as little as a single photon) to the laser’s return. Like the Prophesee event camera, the VoxelSensors’s SPAES returns the pixel location when an event occurs.
While the VoxelSensor’s pixel is more complex than a traditional sensor, it seems simpler than Prophesee’s event camera pixel, but then VoxelSensor requires scanning lasers versus LED. Both are using event sensors to reduce the computational load. I have no idea at this point which will be better at eye tracking.
VoxelSensors with one or more sets of laser scanners and sensors can detect in three dimensions, which is obviously useful for SLAM but might also have advantages for eye tracking.
44:13 Lumotive (LCOS-Based Laser Scanning for LiDAR)
Lumotive has a technology that uses LCOS devices to scan a laser beam. Today, LiDAR systems use a motor-driven rotating prism or a MEMs mirror to scan a laser beam, resulting in a fixed scanning process. The Lumotive method will let them dynamically adjust and change the scanning pattern.
I’ve known Green Light Optics since its founding in 2009 and have worked with them to help me with several optical designs over the years. Greenlight can design and manufacture optics and is located in Cincinnati, Ohio. I ran into GreenLight at the Photonics West exhibit following the AR/VR/MR conference. I thought it would be helpful for other companies that might need optical design and manufacturing to mention them.
“Greenlight Optics is an optical systems engineering and manufacturing company specializing in projection displays, LED and laser illumination, imaging systems, plastic optics, and the integration of optics with electrical and mechanical systems.”
Next Time – Display Devices and Test and Measurement Companies
In the next part of this series will on CES and AR/VR/MR 2023, I plan to cover display devices and a few test and measurement companies.
Update 4/2/2024: Everysight corrected a comment I made about the size of their eyebox.
Introduction
This blog has covered mixed reality (MR) headsets, displays, and optics at CES since 2017 and SPIE’s AR/VR/MR conference since 2019. Both conferences occur in January each year. With this blog’s worldwide reputation (about half of the readers are from outside the U.S.), many companies want to meet. This year, I met with over 50 companies in just one month. Then Apple released the Apple Vision Pro on Feb. 2nd.
As this blog is a one-person operation, I can’t possibly write in detail about all the companies I have met with, yet I want to let people know about them. Last year, in addition to articles on some companies, Brad Lynch of the SadlyIsBradley YouTube channel and I made videos about many companies I met at CES 2023. Then, for AR/VR/MR 2023, I wrote an eight (8) part series of articles on AR/VR/MR. For CES 2024, I wrote a three (3) part series covering many companies.
However, with my Apple Vision Pro (AVP) coverage plus other commitments, I couldn’t see how to cover the over 50 companies I met with in January. While the AVP is such a major product in mixed reality and is important for a broad audience, I don’t want the other companies working on MR headsets, displays, and optics to be forgotten. So, I asked Jason McDowall of The AR Show to moderate a video presentation of the over 50 companies, with each company getting one slide.
Jason and I recorded for about 4 hours (before editing), split over two days, which works out to less than 5 minutes per company. This first hour of the video covers primarily headset companies. I made an exception for the combination of Avegant’s prototype that used Dispelix as it seemed to fit with the headsets.
In editing the video, I realized my presentation was a little “thin” regarding details on some companies. I’m adding some supplementary information and links to this article. I also moved a few companies around in the editing process and re-recorded a couple of sections, so the side numbers don’t always go in order.
Subscription Options Coming to KGOnTech
Between travel expenses and buying an Apple Vision Pro (AVP) with a MacBook for testing the AVP, I spent about $12,000 out of pocket in January and early February alone. Nobody has ever paid to be included (or excluded) in this blog. This blog, which started as a part-time hobby, has become expensive in terms of money and a full-time job. What makes it onto the blog is the tip of the iceberg of time spent on interviews, research, photographing and editing pictures and videos, and travel.
Many companies, including other news outlets and individuals, benefit from this blog indirectly through education or directly via the exposure it gives to large and small companies. Many, if not most, MR industry insiders read this blog worldwide based on my conference interactions. I want to keep the main blog free and not filled with advertising while still reporting on large and small companies. To make financial sense of all this and pay some people to help me, I’m in the process of setting up subscription services for companies and planning on (paid) webinars for individuals. If you or your company might be interested, please email subscriptions@kgontech.com.
Outline of the Video and Additional Information
Below is an outline of the first hour of the video, along with some additional comments and links to more information. The times in blue on the left of each subsection below are the times in the YouTube video discussing a given company.
0:00 Jason McDowall of the AR Show and Karl Guttag of KGOnTech introductions.
My AR/MR design challenge list started with 11 items in a guest article in Display Daily in December 2015 with Sorry, but there is no Santa Claus – Display Daily. Since then, the list has grown to 23.
The key point is that improving any of these items will negatively affect multiple other items. For example, having a wider field of view (FOV) will make the optics bigger, heavier, and more expensive. It will also require a higher resolution display to support the same or better angular resolution, which, in turn, means more pixels requiring more processing, which will need more power, which means bigger batteries and more thermal management. All these factors combine to hurt cost and weight.
I’ve followed Nreal (now Xreal) since its first big splash in the U.S. at CES 2019 (wow, five years ago). Xreal claims to have shipped 300,000 units last year, making it by far the largest unit volume shipper of optical AR headsets.
At CES 2024, Xreal demonstrated a future design that goes beyond their current headsets and adds cameras for image recognition and SLAM-type features.
BMW invited me to a demo of their proof-of-concept glasses-based heads-up display. The demo used Xreal glasses as the display device. BWM had added a head-tracking device under its rearview mirror to lock the user’s view of the car.
But even at CES 2019, Nreal was a case of déjà vu, as it looked so much like a cost-reduced version of the Osterhaut Design Group (ODG) R-9 that I first saw at CES 2017 and started covering and discussing in 2016. The ODG R-9 and the original X-Real had similar birdbath designs and used a Sony 1920×1080 Micro-OLED display. According to a friend of this blog and a former ODG R-9 designer and now CEO of the design firm PulsAR, David Bonelli, there are still some optical advantages of the ODG R-9 that others have yet to copy.
Below is a link to my recent article on CES, which discusses Xreal and my ride wearing the BMW AR demo. I have also included some links to my 2021 teardown of the Nreal birdbath optics and 2016 and 2017 articles about the ODG-R9.
Vuziz was founded in 1997 before making see-through AR devices, no less waveguides, became practical. It now has a wide range of products aimed at different applications. Vuzix founder and CEO Paul Travers has emphasized the need for rugged, all-day wearable AR glasses.
Vuzix historically has primarily had small, lightweight designs, with most later products having a glasses-like form factor. Vuzix originally licensed waveguide technology from Nokia, the same technology Microsoft licensed and later acquired for its Hololens 1. Vuzix says its current waveguide designs are very different from what it licensed from Nokia.
Vuzix’s current waveguide-based products include the monocular BLADE and the biocular SHIELD, which use Texas Instruments DLP displays. Vuzix ‘s latest products are the Ultralight and Ultralight-S, which use Jade Bird Display MicroLEDs driving a waveguide. The current monocular designs use a green-only Jade Bird Display (JBD) with a 640 by 480 resolution and weigh only 34 grams. Vuzix has also announced plans to partner with the French startup Atomistic to develop full-color on a single device, MicroLEDs.
Multiple companies use Vuzix glasses as the headset platform to add other hardware and software layers to make application AR headsets. Xander was at CES with their AI voice-to-text glasses (discussed later). The company 3D2Cuthas AI software that shows unskilled workers where to prune wine grape vines based on inputs from vine pruning experts. At last year’s CES, I met with 360world and their ThermalGlass prototype, which added thermal cameras to a Vuzix headset.
Below are links to my 2024 CES article that included Vuzix, plus a collection of other articles about Vuzix from prior years:
I’ve met with Digilens many times through the years. This year was primarily an update and improvements on this major announcement of their Argo headset from last year (see 2023 article and video via the links below).
Digilens said that in response to my comments last year, they designed an Argo headband variant with a rigid headband that does not rest on the nose and can be flipped up out of view. This new design supports wearing ordinary glasses and is more comfortable for long-term wear. Digilens said many of their customers like this new design variation. A major problem I see with the Apple Vision Pro is the way it is uncomfortably clamped to the face and that it does not flip up like, say, the Lynx MR headset (see also video with Brad Lynch) and Sony MR Headset announced at CES 2024 (which looks very much like the Lynx headset).
Digilens also showed examples of their one-, two-, and three-layer waveguides, which can trade in weight and cost for differences in image quality. They also showed examples of moving the exit grating to different locations in the waveguide.
As I have covered Digilens so much in the past (see links below for some more recent articles), this year’s video was just an update:
Avegant has become a technology development company. They are currently focused on designing small LCOS engines for AR glasses. They presented an update at the AR/VR/MR 2024 conference. Right before the conference, Avegant announced its development of “Spotlight™” to improve contrast by selective illumination of the LCOS panel, similar to LED array LCD TVs with local dimming.
Avengant has shown a very small 30-degree FOV, LCOS-based, 1280×720 pixel, light engine supporting a glasses-like form factor. Avegant’s glasses designs support higher resolution, larger FOV, and a smaller form factor than laser beam scanning or X-Cube-based MicroLEDs (see TCL below). They also got over 1 million nits out of their 30-degree FOV engines. While Avegant designed and built the projector engine and prototype glasses, they used Dispelix waveguides (to be discussed next).
Below are links to blog articles about Avegant’s small LCOS engines:
Dispelix is a waveguide design company, not a headset maker. Avegant, among others, was using Dispelix waveguides (and why they were discussed at this point in the video).
Dispelix presented at the AR/VR/MR conference, where they discussed their roadmap to improve efficiency, reduce “eye glow,” and reduce “rainbow artifacts” caused by diffraction grating light capture.
Dispelix claims to have a roadmap to improve light throughput by a factor of ~4.5 over its current Selva design.
Dispelix, like several other diffractive waveguide companies, including Vuzix and Digilens, uses pantoscopic (front to back) tilt to reduce the eye glow effect, which is common with most other diffractive waveguides (most famously, Hololens). It turns out that for every one-degree of tilt, the “glow” is tilted down by two degrees such that with just a few degrees of tilt, the glow is projected well below most people’s view. Displelix has said that a combination of grating designs and optical coatings can nearly eliminate the glow in future designs.
Another problem (not discussed in the video) that has plagued diffractive waveguides has been the “rainbow artifact” caused by external light, particularly overhead from in front or behind the waveguide, being directed to the eye from the diffraction gratings. Because the gratings effect is wavelength-dependent, the light is broken into multiple colors (like a rainbow). Dispelix says they are developing designs that will direct the unwanted external light away from the eye.
I met with Jeri Ellsworth, the CEO of Tilt-Five, at CES. In addition to getting an update on Tilt-Five (with nothing I can’t talk about), Jeri and I discussed our various histories working on video game hardware, graphics co-processors, and augmented reality.
BTW, Jeri Ellsworth, Jason McDowall, Adi Robertson (editor at The Verge), Ed Tang (CEO of Avegant), and I are slated to be on a panel discussion at AWE 2024.
Below are some links to my prior reporting on Tilt-Five.
Sightful’s Spacetop is essentially a laptop-like keyboard and computer with Xreal-type birdbath optics using 1920×1080 OLED microdisplays with a 52-degree FOV. Under the keyboard are the processing system (Qualcomm Snapdragon XR2 Kryo 585TM 8-core 64-bit CPU and AdrenoTM 650 GP), memory (8GB), flash (128GB), and battery (5 hours of typical use). The system runs a “highly modified” Android operating system.
I saw Sightful at the Show Stoppers media event at CES, and they were nice enough to bring me custom prescription inserts to the AR/VR/MR conference. Sightful’s software environment supports multiple virtual- monitors/windows of various sizes, which are clipped to the glasses’ 1920×1080, 52-degree view. I believe the system uses the inertial sensors in the headset to make the virtual monitors appear stationary as opposed to the more advanced SLAM (simultaneous localization and mapping) used by many larger headsets.
As a side note, my first near-eye-display work in 1998 was on a monocular headset to be used with laptops as a private display when traveling. I designed the 1024×768 (high resolution for a 1998 microdisplay) LCOS display device and its controller. The monocular headset used color sequential LED illumination with birdbath mirror optics. Given the efficiency and brightness of LEDs of the day, it was all we could do to make a non-see-through monocular device. Unfortunately, the dot-com bust happened in 1999, which took out many high-tech startups.
Nimo’s “Spatial Computing” approach is slightly different from Sightful’s. Instead of combining the computing hardware with the keyboard like Sightful, Nimo has a small computing and battery module that works as a 3-D spatial mouse with a trackpad (on top). Nimo has a USB-C connection for AR glasses, WiFi 6, and Bluetooth 5.1 for communication with an (optional) wireless keyboard.
The computing specs resemble Sightful’s, with a Qualcomm® XR2 8-core CPU, 8GB RAM, and 128GB Storage. Nimo supports working with Rokid, Xreal, and its own LetinAR-Optics-based 1920×1080 OLED AR glasses via its USB-C port, which provides display information and power.
Like Sightful, Nimo has a modified Android Operating system that supports multiple virtual monitors/windows. It uses the various glasses’ internal sensors to detect head movement to keep the monitors stationary in 3-D space as the user’s head moves.
I wrote about Nimo Planet in my 2024 CES coverage:
Lumen is a headset for blind people that incorporates lidar, cameras, and other sensors. Rather than outputting a display image, it provides haptic and audible feedback to the user. I don’t know how to judge this technology, but it seems like an interesting case where today’s technology could help people.
Ocutrx’s OcuLenz was initially aimed at helping people with macular degeneration and other forms of low vision. However, at the Ocutrx booth on its website at the CES ShowStoppers event, Ocutrx emphasized that the headset could be used for more than low vision, including gamers, surgeons, and military personnel. The optical design was done by an old friend, David Kessler, whom I ran into at the Ocutrx booth at CES and the AR/VR/MR conference.
The Oculenz uses larger-than-typical birdbath optics to support a 72-degree (diagonal) FOV. It uses 2560 x 1440 pixels per eye, so they will have a similar angular resolution but wider FOV than the more common 1920×1080 birdbath glasses (e.g., Xreal), which typically have 45- to ~50-degree FOVs. Unlike the typical birdbath glasses, which have separate processing, the Oculenz integrates a Qualcomm Snapdragon® XR2 processor, Wi-Fi, and cellular connectivity. This headset was originally aimed at people with low vision as a stand-alone device.
I wrote about Ocutrx and some of the issues of funding low-vision glasses in my earlier report on CES 2024, linked below:
Everysight has AR glasses in a glasses-like form factor. They are designed to be self-contained, weigh only 47 grams, and have no external wiring. They use a 640×400 pixel full-color OLED display and can achieve >1000 nits to the eye.
Everysight uses a “Pre-Compensated Off-Axis” optical design, which tends to get more than double the light from the display to the eye while enabling more than three times the real-world light to pass through the display area compared to birdbath (e.g., Xreal) designs. With this design, the pre-compensation optics pre-correct for hitting the curved semi-mirror combiner off-axis. Typically, this mirror will be 50% or less reflective and only has to be applied over where the display is to be seen.
However, the Everysight glasses only support a rather small 22-degree FOV, and the eyebox is rather small. While Everysight has reduced the panoscopic tilt of the lenses over prior models, the latest Maverick modes still tilt toward the user’s cheeks more than most common glasses.
UPDATE 4/2/2024: Everysight responded to my original eyebox comment, “With respect to the eyebox, we take care of that with different sizes (Maverick today has two sizes – Medium and Large). The important part is that once you have the correct size, glass or eye movements won’t take you out of the eyebox. We believe that this is a much better tradeoff than a one-size-fits-all [with] low optical efficiency and enables you to use OLEDs in sunny days outdoors, even with clear visors.“
Thus far, Everysight seems to be marketing its glasses more to the sports market, which needs s, lightight headsets with bright displays for outdoor use.
If vision correction is not required, the lenses can be easily swapped out for various types of tint. More recently, Everysight has been able to support prescription lenses. For prescriptions, the inner curved mirror corrects for the virtual image, and a corrective lens on the outside corrects for the real world, including correcting for the curvature of the inner surface with the semi-mirror.
Everysight spun out of the large military company ELBIT, which perfected the pre-compensated off-axis design for larger headsets. This optical design is famously used in the F35 helmet and, more recently, in the civilian aircraft Skylens head-wearable HUD display, which has received FAA approval for use in multiple civilian aircraft, including recently the 737ng family.
Everysight was discussed in my CES 2024 coverage linked to below:
At CES 2024, TCL showed their RayNex X2 and their newer X2 Light. I have worked with 3-chip LCOS projectors with an X-Cube in the past, and I was curious to see the image quality as I know from experience aligning to X-Cubes is non-trivial, particularly with the smaller sizes of the Jade Bird Display red, green, and blue MicroLED displays.
Overall, the newer X2 Lite using the Applied Materials (AMAT) waveguides looked much better than the earlier RayNeo X2 (non-Lite). Even the AMAT had significant front projection, but as discussed with respect to Displelix above, this problem can be managed, at least for smaller FOVs (the RayNeo X2s have a ~30-degree diagonal FOV).
I covered the TCL color µLED in more detail in my CES 2024 coverage (link below). I have also included links to articles discussing the Jade Bird Displays MicroLEDs and their use of an X-Cub for a color combiner:
Mojie/Meta Bound showed 640×480 green-only MicroLED-based glasses claiming 3,000 nits (to the eye), 90% transparency (without tinting), a 28-degree FOV, and a weight of only 38 grams. These were also wireless and, to a first approximation, very similar to Vuzix UltraLite. One thing that makes them stand out is that they use a waveguide technology made of plastic resin (most use glass).
Many companies are experimenting with plastic waveguides to reduce weight and improve safety. So far, the color uniformity with full-color displays has been worse than with glass-based waveguides. However, the uniformity issues are less noticeable with a monochrome (green) display. Mitsui Chemicals and Mitsubishi Chemicals, both of Japan, are suppliers of resin plastic substrate material for waveguides.
Below is a link to my article on Mojie/Meta Bounds in my CES 2024 coverage:
Canon had a fun demo based on the 100+ camera Free Viewpoint Video System VR system. Basically, you could sit around a table and see a basketball game (I think it was the 2022 NBA All-Stars Game) played on that table from any angle. Canon has been working on this technology for a decade or more, with demos for both basketball and soccer (football). While it’s an interesting technology demo, I don’t see how this would be a great way to watch a complete game. Even with over 100 cameras and the players being relatively small (far away virtually), one could see gaps where that the cameras couldn’t cover.
Canon also showed a very small passthrough AR camera and lens setup. While it was small, the FOV and video quality were not impressive. Brad Lynch of SadlyItsBradley found it to be pointless.
I have personally purchased a lot of Canon camera equipment over the last 25 years (including my Canon R5, which I take pictures with for this blog), so I am not in any way against Canon. However, as I discussed with Brad Lynch about Canon’s booth at CES 2023 (YouTube Link), I can’t see where Canon is going or what message they are trying to send in terms of mixed reality despite their very large and expensive booth. On the surface, Canon seems to be dabbling in various MR technologies, but it is not moving in a clear direction.
Solos makes audio-only glasses similar to the Meta/RayBand Wayfarer (but without cameras). These glasses emphasize modular construction, with all the expensive “smarts” in the temples so that the front-part lenses can be easily swapped.
Like several others, Solos uses cellular communication to connect to ChatGPT to do on-the-fly translations. What makes Solos more interesting is that Its Chairman is John Fan, also the chairman of Lightning Silicon Technology (a spinoff of Kopin Displays), a maker of OLED Microdisplays. At Lighting Silicon’s CES 2024 suite, John Fan discussed that incorporating the displays into the Solos glasses was an obvious future step.
While I saw Xander in the AARP sponsor AgeTech Summit booth at CES 2024, I didn’t get to meet with them. Xander hits at a couple of issues I feel are important. First, they show how AR technology can be used to help people. Secondly, they show what is expected to be a growing trend of adding basic visual information to augment audio.
As I wrote last time, I met with nearly 40 companies at CES, of which 31 I can talk about. This time, I will go into more detail and share some photos. I picked the companies for this article because they seemed to link together. The Sony XR headset and how it fit on the user’s head was similar to the newer DigiLens Argo headband. DigiLens and the other companies had diffractive waveguides and emphasized lightweight and glass-like form factors.
I would like to caution readers of my saying that “all demos at conferences are magic shows,” something I warn about near the beginning of this blog in Cynics Guide to CES – Glossary of Terms). I generally no longer try to take “through the optics” pictures at CES. It is difficult to get good representative photos in the short time available with all the running around and without all the proper equipment. I made an exception for the TCL color MicroLED glasses as they readily came out better than expected. But at the same time, I was only using test images provided by TCL and not test patterns that I selected. Generally, the toughest test patterns (such as those on my Test Pattern Page) are simple. For example, if you put up a solid white image and see color in the white, you know something is wrong. When you put up colorful pictures with a lot of busy detail (like a colorful parrot in the TCL demo), it is hard to tell what, if anything, is wrong.
Sony XR and DigiLens Headband Mixed Reality (with contrasts to Apple Vision Pro)
Sony XR (and others compared to Apple Vision Pro)
This blog expressed concerns about the Apple Vision Pro’s (AVP) poor mechanical ergonomics (AVP), completely blocking peripheral vision and the terrible placement of the passthrough cameras. My first reaction was that the AVP looked like it was designed by a beginner with too much money and an emphasis on style over functionality. What I consider Apple’s obvious mistakes seem to be addressed in the new Sony XR headset (SonyXR).
The SonyXR shows much better weight distribution, with (likely) the battery and processing moved to the back “bustle” of the headset and a rigid frame to transfer to the weight for balance. It has been well established that with designs such as the Hololens 2 and Meta Quest Pro, this type of design leads to better comfort. This design approach can also move a significant amount of power to the back for better heat management due to having a second surface radiating heat.
The bustle on the back design also avoids the terrible design decision by Apple to have a snag hazard and disconnection nuisance with an external battery and cable.
The SonyXR is shown to have enough eye relief to wear typical prescription glasses. This will be a major advantage in many potential XR/MR headset uses, making it more interchangeable. This is particularly important for use cases that are not all-day or one-time (ex., museum tours, and other special events). Supporting enough eye relief for glasses is more optically difficult and requires larger optics for the same field of view (FOV).
Another major benefit of the larger eye relief is that it allows for peripheral vision. Peripheral vision is considered to start at about 100 degrees or about where a typical VR headset’s FOV stops. While peripheral vision is low in resolution, it is sensitive to motion. It alerts the person to motion so they will turn their head. The saying goes that peripheral vision evolved to keep humans from being eaten by tigers. This translated to the modern world, being hit by moving machinery and running into things that might hurt you.
Another good feature shown in the Sony XR is the flip-up screen. There are so many times when you want to get the screen out of your way quickly. The first MR headset I used that supported this was the Hololens 2.
Another feature of the Hololens 2 is the front-to-back head strap (optional but included). Longtime VR gamer and YouTube personality Brad Lynch of the SadlyItsBradley YouTube channel has tried many VR-type headsets and optional headbands/straps. Brad says that front-to-back straps/pads generally provide the most comfort with extended use. Side-to-side straps, such as on the AVP, generally don’t provide the support where it is needed most. Brad has also said that while a forehead pad, such as on the Meta Quest Pro, helps, headset straps (which are not directly supported on the MQP) are still needed. It is not clear whether the Sony XR headset will have over-the-head straps. Even companies that support/include overhead straps generally don’t show them in the marketing photos and demos as they mess up people’s hair.
The SonyXR cameras are located closer to the user’s eyes. While there are no perfect placements for the two cameras, the further they are from the actual location of the eyes, the more distortion will be caused for making perspective/depth-correct passthrough (for more on this subject, see: Apple Vision Pro Part 6 – Passthrough Mixed Reality (PtMR) Problems).
Lynx also used the headband with a forehead pad, with the back bustle and flip-up screen. Lynx also supports enough eye relief for glasses and good peripheral vision and locates their passthrough cameras near where the eye will be when in use. Unfortunately, I found a lot of problems with the optics Lynx chose for the R1 by the optics design firm Limbak (see also my Lynx R1 discussion with Brad Lynch). Apple has since bought Limbak, and it is likely Lynx will be moving on with other optical designs.
Digilens Argo New Head Band Version at CES 2024
I wrote a lot about Digilens Argo in last year’s coverage of CES and the AR/VR/MR conference in DigiLens, Lumus, Vuzix, Oppo, & Avegant Optical AR (CES & AR/VR/MR 2023 Pt. 8). In the section Skull-Gripping “Glasses” vs. Headband or Open Helmet, I discussed how Digilens has missed an opportunity for both comfort and supporting the wearing of glasses. Digilens said they took my comments to heart and developed a variation with the rigid headband and flip-up display shown in their suite at CES 2024. Digilens said that this version let them expand their market (and no, I didn’t get a penny for my input).
The Argos are light enough that they probably don’t need an over-the-head band for extra support. If the headband were a ground-up design rather than a modular variation, I would have liked to see the battery and processing moved to a back bustle.
While on the subject of Digilens, they also had a couple of nice static displays. Pictured below right are variations in waveguide thickness they support. Generally, image quality and field of view can be improved by supporting more waveguide layers (with three layers supporting individual red, green, and blue waveguides). Digilens also had a static display using polarized light to show different configurations they can support for the entrance, expansion, and exit gratings (below right).
Vuzix
Vuzix has been making wearable heads-up displays for about 26 years and has a wide variety of headsets for different applications. Vuzix has been discussed on this blog many times. Vuzix primarily focuses on lightweight and small form factor glasses and attachments with displays.
Vuzix Ultralite Sport (S) and Forward Projection (Eye Glow) Elimination
New this year at CES was Vuzix’s Ultralite Sports (S) model. In addition to being more “sporty” looking, their waveguides are designed to eliminate forward projection (commonly referred to as “Eye Glow”). Eye glow was famously an issue with most diffractive waveguides, including the Hololens 1 & 2 (see right), Magic Leap 1 & 2, and previous Vuzix waveguide-based glasses.
If the lenses are canted (tilted), the exit gratings, when designed to project to the eye, will then project down at twice the angle at which the waveguides are canted. Thus, with only a small change in the tilt of the waveguides, the projection will be far below the eyesight of others (unless they are on the ground).
Ultra Light Displays with Audio (Vuzix/Xander) & Solos
Last year, Vuzix introduced their lightweight (38 grams) Z100 Ultralite, which uses 640×480 green (only) MicroLED microdisplays. Xander, using the lightweight Vuzix’s Z100, has developed text-to-speech glasses for people with hearing difficulties (Xander was in the AARP booth at CES).
While a green-only display with low resolution by today’s standards is not something you will want to watch movies, there are many uses for having a limited amount of text and graphics in a lightweight and small form factor. For example, I got to try out Solos Audio glasses, which, among other things, use ChatGPT to do on-the-fly language translation. It’s not hard to imagine that a small display could help clarify what is being said about Solos and similar products, including the Amazon Echo Frames and the Ray-Ban Meta Wayfarer.
Mojie (Green) MicroLED with Plastic Waveguide
Like Vuzix Z100, the Mojie (a trademark of Meta-Bounds) uses green-only Jade Bird Display 640×480 microLEDs with waveguide optics. The big difference is that Mojie, along with Oppo Air 2 and Meizu MYVU, all use Meta-Bounds resin plastic waveguides. Unfortunately, I didn’t get to the Mojie booth until near closing time at CES, but they were nice enough to give me a short demo. Overall, regarding weight and size, the Mojie AR glasses are similar to the Vuzix Z100, but I didn’t have the time and demo content to judge the image quality. Generally, resin plastic diffractive waveguides to date have had lower image quality than ones on a glass substrate.
I have no idea what resin plastic Meta-Bounds uses or if they have their own formula. Mitsui Chemicals and Mitsubishi Chemicals, both of Japan, are known to be suppliers of resin plastic substrate material.
EverySight
ELBIT F35 Helmet and Skylens
Everysight (the company, not the front eye display feature on the Apple Vision Pro) has been making lightweight glasses primarily for sports since about 2018. Everysight spun out of the major defense (including the F35 helmet HUD) and commercial products company ELBIT. Recently, ELBIT had their AR glasses HUD approved by the FAA for use in the Boeing 737ng series. EverySight uses an optics technology, which I call “precompensated off-axis.” Everysight (and ELBIT) have an optics engine that projects onto a curved front lens with a partial mirror coating. The precompensation optics of the projector correct for the distortion from hitting a curved mirror off-axis.
The Everysight/Elbit technology is much more optically efficient than waveguide technologies and more transparent than “birdbath technologies” (the best-known birdbath technology today being Xreal). The amount of light from the display versus transparency is a function of the semi-transparent mirror coating. The downside of the Eversight optical system with small-form glasses is that the FOV and Eyebox tend to be smaller. The new Everysight Maverick glasses have a 22-degree FOV and produce over 1,000 nits using a 5,000 nit 640×400 pixel full-color Sony Micro-OLED.
The front lens/mirror elements are inexpensive and interchangeable. But the most technically interesting thing is that Everysight has figured out how to support prescriptions built into the front lens. They use a “push-pull” optics arrangement similar to some waveguide headsets (most notably Hololens 1&2 and Magic Leap). The optical surface on the eye side of the lens corrects for the virtual display of the eye, and the optical surface on the outside surface of the lens is curved to do what is necessary to correct vision correction for the real world.
TCL RayNeo X2 and Ray Neo X2 Lite
I generally no longer try to take “through the optics” pictures at CES. It is very difficult to get good representative photos in the short time available with all the running around and without all the proper equipment. I got some good photos through TCL’s RayNeo X2 and the RayNeo X2 Lite. While the two products sound very close, the image quality with the “Lite” version, which switched to using Applied Materials (AMAT) diffractive waveguides, was dramatically better.
The older RayNeo X2s were available to see on the floor and had problems, particularly with the diffraction gratings capturing stray light and the general color quality. I was given a private showing of the newly announced “Lite” version using the AMAT waveguides, and not only were they lighter, but the image quality was much better. The picture on the right below shows the RayNeo X2 (with an unknown waveguide) on the left that captures the stray overhead light (see streaks at the arrows). The picture via the Lite model (with the AMAT waveguide) does not exhibit these streaks, even though the lighting is similar. Although hard to see in the pictures, the color uniformity with the AMAT waveguide also seems better (although not perfect, as discussed later).
Both RayNeo models use 3-separate Jade Bird Display red, green, and blue MicroLEDs (inorganic) with an X-cube color combiner. X-cubes have long been used in larger LCD and LCOS 3-panel projectors and are formed with four prisms with different dichroic coatings that are glued together. Jade Bird Display has been demoing this type of color combiner since at least AR/VR/MR 2022 (above). Having worked with 3-Panel LCOS projectors in my early days at Syndiant, I know the difficulties in aligning three panels to an X-cube combiner. This alignment is particularly difficult with the size of these MicroLED displays and their small pixels.
I must say that the image quality of the TCL RayNeo X2 Lite exceeded my expectations. Everything seems well aligned in the close-up crop from the same parrot picture (below). Also, there seems to be relatively good color without the wide variation from pixel-to-pixel brightness I have seen in past MicroLED displays. While this is quite an achievement for a MicroLED system, the RayNeo X2 light only has a modest 640×480 resolution display with a 30-degree diagonal FOV. These specs result in about 26 pixels per degree or about half the angular resolution of many other headsets. The picture below was taken with a Canon R5 with a 16mm lens, which, as it turns out, has a resolving power close to good human vision.
Per my warning in the introduction, all demos are magic shows. I don’t know how representative this prototype will be of units in production, and perhaps most importantly, I did not try my test patterns but used the images provided by TCL.
Below is another picture of the parrot taken against a darker background. Looking at the wooden limb under the parrot, you will see it is somewhat reddish on the left and greenish on the right. This might indicate color shifting due to the waveguide, as is common with diffractive waveguides. Once again, taking quick pictures at shows (all these were handheld) and without controlling the source content, it is hard to know. This is why I would like to acquire units for extended evaluations.
The next two pictures, taken against a dark background and a dimly lit room, show what I think should be a white text block on the top. But the text seems to change from a reddish tint on the left to a blueish tint on the right. Once again, this suggests some color shifting across the diffractive waveguide.
Below is the same projected image taken with identical camera settings but with different background lighting.
Below is the same projected flower image with the same camera settings and different lighting.
Another thing I noticed with the Lite/AMAT waveguides is significant front projection/eye glow. I suspect this will be addressed in the future, as has been demonstrated by Digilens, Displelix, and Vuzix, as discussed earlier.
Conclusions
The Sony XR headset seems to showcase many of the beginner mistakes made by Apple with the AVP. In the case of the Digilens Argo last year, they seemed to be caught between being a full-featured headset and the glasses form factor. The new Argo headband seems like a good industrial form factor that allows people to wear normal glasses and flip the display out of the way when desired.
Vuzix, with its newer Ultralite Z100 and Sports model, seems to be emphasizing lightweight functionality. Vuzix and the other waveguide AR glasses have not given a clear path as to how they will support people who need prescription glasses. The most obvious approach they will do some form of “push-pull” with a lens before and after the waveguides. Luxexcel had a way to 3-D print prescription push-pull lenses, but Meta bought them. Add Optics (formed by former Luxexcel employees) has another approach with 3-D printed molds. Everysight tries to address prescription lenses with a somewhat different push-pull approach that their optical design necessitates.
While not perfect, the TCL color MicroLED, at least in the newer “Lite” version, was much better than I expected. At the same time, one has to recognize the resolution, FOV, and color uniformity are still not up to some other technologies. In other words, to appreciate it, one has to recognize the technical difficulty. I also want to note that Vuzix has said that they are also planning on color MicroLED glasses with three microdisplays, but it is not clear whether they will use an X-cube or a waveguide combiner approach.
The moderate success of smart audio glasses may be pointing the way for these ultra-light glasses form factor designs for a consumer AR product. One can readily see where adding some basic text and graphics would be of further benefit. We will know if this category has become successful if Apple enters this market 😁.
Introduction – Contrast in Approaches and Technologies
This article will compare and contrast the Vuzix Ultralight, Lumus Z-lens, and DigiLens Argo waveguide-based AR prototypes I saw at CES 2023. I discussed these three prototypes with SadlyItsBradly in our CES 2023 video. It will also briefly discuss the related Avegant’s AR/VR/MR 2022 and 2023 presentations about their new smaller LCOS projection engine and Magic Leap 2’s LCOS design to show some other projection engine options.
It will go a bit deeper into some of the human factors of the Digitlens’ Argo. Not to pick on Digilens’ Argo, but because it has more features and demonstrates some common traits and issues of trying to support a rich feature set in a glasses-like form factor.
When I quote various specs below, they are all manufacturer’s claims unless otherwise stated. Some of these claims will be based on where the companies expect the product to be in production. No one has checked the claims’ veracity, and most companies typically round up, sometimes very generously, on brightness (nits) and field of view (FOV) specs.
This is a somewhat long article, and the key topics discussed include:
MicroLED versus LCOS Optical engine sizes
The image quality of MicroLED vs. LCOS and Reflective (Lumus) vs. Diffractive waveguides
The efficiency of Reflective vs. Diffractive waveguides with MicroLEDs
The efficiency of MicroLED vs. LCOS
Glasses form factor (using Digilens Argo as an example)
They are each about 38 grams in weight, including frames, processing, wireless communication, and batteries, and wirelessVuzix developed their own diffractive waveguide and support about a 30-degree FOV. Both are self-contained with wireless, with an integrated battery and processing.
Vuzix developed their own glass diffractive waveguides and optical engines for the Ultralight. They claim a 30-degree FOV with 3,000 nits.
Oppo uses resin plastic waveguides, and MicroLED optical engine developed jointly with Meta Bounds. I have previously seen prototype resin plastic waveguides from other companies for several years. This is the first time I have seen them in a product getting ready for production. The glasses (described in a 1.5-minute YouTube/CNET video) include microphones and speakers for applications, including voice-to-text and phone calls. They also plan on supporting vision correction with lenses built into the frames. Oppo claims the Air Glass 2 has a 27-degree FOV and outputs 1,400 nits.
Lumus Z-Lens
Lumus’s Z-Lens (third from the top right) supports up to a 2K by 2K full/true color LCOS display with a 50-degree FOV. Its FoV is 3 to 4 times the area of the other three headsets, so it must output more than 3 to 4 times the total light. It supports about 4.5x the number of pixels of the DigiLens Argo and over 13x the pixels of the Vuzix Ultralite and Oppo Air Glass 2.
The Z-Lens prototype is a demonstration of display capability and, unlike the other three, is not self-contained and has no battery or processing. A cable provides the display signal and power for each eye. Lumus is an optics waveguide and projector engine company and leaves it to its customers to make full-up products.
Digilens Argo
The DigiLens Argo (bottom, above right) uses a 1280 by 720 full/true color LCOS display. The Argo has many more features than the other devices, with integrated SLAM cameras, GNSS (GPS, etc.), Wi-Fi, Bluetooth, a 48mp (with 4×4 pixel “binning” like the iPhone 14) color camera, voice recognition, batteries, and a more advanced CPU (Qualcomm Snapdragon 2). Digilens intends to sell the Argo for enterprise applications, perhaps with partners, while continuing to sell waveguides optical engines as components for higher-volume applications. As the Argo has a much more complete feature set, I will discuss some of the pros and cons of some of the human factors of the Argo design later in this article.
Through the Lens Images
Below is a composite image from four photographs taken with the same camera (OM-D E-M5 Mark III) and lens (fixed 17mm). The pictures were taken at conferences, handheld, and not perfectly aligned for optimum image quality. The projected display and the room/outdoor lighting have a wide range of brightness between the pictures. None of the pictures have been resized, so the relative FoVs have been maintained, and you get an idea of the image content.
The Lumus Z-lens reflective waveguide has a much bigger FOV, significantly more resolution, and exhibits much better color uniformity with the same or higher brightness (nits). It also appears that reflective waveguides have a significant efficiency advantage with both MicroLEDs (and LCOS), as discussed in MicroLEDs with Waveguides (CES & AR/VR/MR 2023 Pt. 7). It should also be noted that the Lumus Z-lens prototype has only the display with optics and has no integrated processing, communication or battery. In contrast, the others are closer to full products.
A more complex issue is that of power consumption versus brightness. LCOS engines today are much more efficient for an image with full-screen bright images (by 10x or more) than MicroLEDs with similar waveguides. MicroLED’s big power advantage occurs when the content is sparse, as the power consumption is roughly proportional to the average pixel value, whereas, with LCOS, the whole display is illuminated regardless of the content.
If and when MicroLEDs support full color, the efficiency of nits-per-Watt will be significantly lower than monochrome green. Whatever method produces full color will detract from the overall electrical and optical efficiency. Additionally, color balancing for white requires adding blue and red light with lower nits-per-Watt.
Some caveats:
The Lumus Z-Lens is a prototype and does not have all the anti-reflective and other coatings of a production waveguide. Lumus uses an LCOS device with about ~3-micron pixels, which fits 1440 by 1440 within the ~50-degree FOV supported by the optics. Lumus is working with at least one LCOS maker to get an ~2-micron pixel size to support 2K by 2K resolution with the same size display. The image is cut off on the right-hand side of the image by the camera, which was rotated into portrait mode to fit inside the glasses.
The Digilens through the lens image is from Photonics West in 2022 (about one year old). Digilens has continued to improve its waveguide since this picture was taken.
The Vuzix picture was taken via Vuzix Shield, which uses the same waveguide and optics as the Vuzix Ultralight.
The Oppo image was taken at the AR/VR/MR 2023 conference.
Optical Engine Sizes
Vuzix has an impressively small optical engine driving Vuzix’s diffractive waveguides. Seen below left is a comparison of Vuzix’s older full-color DLP engine compared with an in-development color X-Cube engine and the green MicroLED engine used in the Vuzix Ultralite™ and Shield. In the center below is an exploded view of the Oppo and Meta Bound glasses (joint design as they describe it) with their MicroLED engine shown in their short CNET YouTube video. As seen in the still from the Oppo video, they have plans to support vision correction built into the glasses.
Below right is the Digilens LCOS engine, which uses a fairly conventional LCOS (using Ominivision’s LCOS device with driver ASIC showing). The dotted line indicates where the engine blocks off the upper part of the waveguide. This blocked-off area carries over to the Argo design.
The Digilens Argo, with its more “conventional” LCOS engine, requires are large “brow” above the eye to hide it (more on this issue later). All the other companies have designed their engine to avoid this level of intrusion into the front area of the glasses.
Lumus had developed their 1-D pupil-expanding reflective waveguide for nearly two decades, which needed a relatively wide optical engine. With the 2-D Maximus waveguide in 2021 (see: Lumus Maximus 2K x 2K Per Eye, >3000 Nits, 50° FOV with Through-the-Optics Pictures), Lumus demonstrated their ability to shrink the optical engine. This year, Lumus further reduced the size of the optical engine and its intrusion into the front lens area with their new Z-lens design (compare the two right pictures below of Maximus to Z-Lens)
Shown below are frontal views of the four lenses and their optical engines. The Oppo Air Glass 2 “disguises” the engine within the industrial design of a wider frame (and wider waveguide). The Lumus Z-Lens, with a full color about 3.5 times the FOV as the others, has about the same frontal intrusion as the green-only MicroLED engines. The Argo (below right) stands out with the large brow above the eye (the rough location of the optical engine is shown with the red dotted line).
Lumus Removes the Need for Air Gaps with the Z-Lens
Another significant improvement with Lumus’s Z-Lens is that unlike Lumus’s prior waveguides and all diffractive waveguides, it does not require an air gap between the waveguide’s surface and any encapsulating plastics. This could prove to be a big advantage in supporting integrated prescription vision correction or simple protection. Supporting air gaps with waveguides has numerous design, cost, and optical problems.
A typical full-color diffractive waveguide typically has two or three waveguides sandwiched together, with air gaps between them plus an air gap on each side of the sandwich. Everywhere there is an air gap, there is also a desire for antireflective coatings to remove reflections and improve efficiency.
Avegant and Magic Leap Small LCOS Projector Engines
Older LCOS projection engines have historically had size problems. We are seeing new LCOS designs, such as the Lumus Z-lens (above), and designs from Avegant and Magic Leap that are much smaller and no more intrusive into the lens area than the MicroLED engines. My AR/VR/MR 2022 coverage included the article Magic Leap 2 at SPIE AR/VR/MR 2022, which discusses the small LCOS engines from both Magic Leap and Avegant. In our AWE 2022 video with SadlyItsBradley, I discuss the smaller LCOS engines by Avegant, Lumus (Maximus), and Magic Leap.
Below is what Avegant demonstrated at AR/VR/MR 2022 with their small “L” shaped optical engines. These engines have very little intrusion into the front lenses, but they run down the temple of the glasses, which inhibits folding the temple for storage like normal glasses.
At the AR/VR/MR 2023, Avegant showed a newer optical design that reduced the footprint of their optics by 65%, including shortening them to the point that the temples can be folded, similar to conventional glasses (below left). It should be noted that what is called a “waveguide” in the Avegant diagram is very different from the waveguides used to show the image in AR glasses. Avegants waveguide is used to illuminate the LCOS device. Avengant, in their presentation, also discussed various drive modes of the LEDs to give higher brightness and efficiency with green-only and black-and-white modes. The 13-minute video of Avegant’s presentation is available at the SPIE site (behind SPIE’s paywall). According to Avegant’s presentation, the optics are 15.6mm long by 12.4mm wide, support a 30-degree FOV, with 34 pixels/degree, and 2 lumens of output in full color and up to 6 lumens in limited color outdoor mode. According to the presentation, they expect about 1,500 nits with typical diffractive waveguides in the full-color mode, which would roughly double in the outdoor mode.
The Magic Leap 2 (ML2) takes reducing the optics one step further and puts the illumination LEDs and LCOS on opposite sides of the display’s waveguide (below and described in Magic Leap 2 at SPIE AR/VR/MR 2022). The ML2 claims to have 2,000 nits with a much larger 70-degree FOV.
Transparency (vs. Birdbath) and “Eye Glow”
Transparency
As seen in the pictures above, all the waveguide-based glasses have transparency on the order of 80-90%. This is a far cry from the common birdbath optics, with typically only 25% transparency (see Nreal Teardown: Part 1, Clones and Birdbath Basics). The former Osterhout Design Group (ODG) made birdbath AR Glasses popular first with their R6 and then with the R8 and R9 models (see my 2017 article ODG R-8 and R-9 Optic with OLED Microdisplays) which served as the models for designs such at Nreal and Lenovo’s A3.
OGD Legacy and Progress
Several former ODG designers have ended up at Lenovo, the design firm Pulsar, Digilens, and elsewhere in the AR community. I found pictures of Digilens VP Nima Shams wearing the ODG R9 in 2017 and the Digilens Argo at CES. When I showed the pictures to Nima, he pointed out the progress that had been made. The 2023 Argo is lighter, sticks out less far, has more eye relief,is much more transparent, has a brighter image to the eye, and is much more power efficient. At the same time, it adds features and processing not found on the ODG R8 and R9.
Front Projection (“Eye Glow”)
Another social aspect of AR glasses is Front Projection, known as “Eye Glow.” Most famously, the Hololens 1 and 2 and the Magic Leap 1 and 2 project much of the light forward. The birdbath optics-based glasses also have front projection issues but are often hidden behind additional dark sunglasses.
When looking at the “eye glow” pictures below, I want to caution you that these are random pictures and not controlled tests. The glasses display radically different brightness settings, and the ambient light is very different. Also, front projection is typically highly directional, so the camera angle has a major effect (and there was no attempt to search for the worst-case angle).
In our AWE 2022 Video with SadlyItsBradley, I discussed how several companies, including Dispelix, are working to reduce front projection. Digilens is one of the companies I discussed that has been working to reduce front projection. Lumus’s reflective approach has inherent advantages in terms of front projection. DigiLens Argo (pictures 2 and 3 from the right) have greatly reduced their eye glow. The Vuzix Shield (with the same optics as the Ultralite) has some front projection (and some on my cheek), as seen in the picture below (4th from the left). Oppo appears to have a fairly pronounced front projection, as seen in two short videos (video 1 and video 2)
DigiLens Argo Deeper Look
DigiLens has been primarily a maker of diffractive waveguides, but it has, through the years, made several near-product demonstrations in the past. A few years ago, they when through a major management change (see 2021 article, DigiLens Visit), and with the management came changes in direction.
Argo’s Business Model
I’m always curious when a “component company” develops an end product. I asked DigiLens to help clarify their business approaches and received the following information (with my edits):
Optical Solutions Licensing – where we provide solutions to our license to build their own waveguides using our scalable printing/contactless copy process. Our licensees can design their waveguides, which Digilens’ software tools enable. This business is aimed at higher-volume applications from larger companies, mostly focused on, but not limited to, the consumer side of the head-worn market.
Enterprise/Industrial Products – ARGO is the first product from DigiLens that targets the enterprise and industrial market as a full solution. It will be built to scale and meet its target market’s compliance and reliability needs. It uses DigiLens optical technology in the waveguides and projector and is built by a team with experience shipping thousands of enterprise & Industrial glasses from Daqri, ODG, and RealWear.
Image Quality
As I was familiar with Digilen’s image quality, I didn’t really check it out that much with the ARGO, but rather I was interested in the overall product concept. Over the last several years, I have seen improved image quality, including uniformity and addressing the “eye glow” issue (discussed earlier).
For the type of applications in the “enterprise market” ARGO is trying to serve, absolute image quality may not be nearly as important as other factors. As I have often said, “Hololens 2 proves that image quality for the customers that use it” (see this set of articles discussing the Hololen 2’s poor image quality). For many AR markets, the display information is simple indicators such as arrows, a few numbers, and lines. It terms of color, it may be good enough if only a few key colors are easily distinguishable.
Overall, Digilens has similar issues with color uniformity across the field of view of all other diffractive waveguides I have seen. In the last few years, they have gone from having poor color uniformity to being among the better diffractive waveguides I have seen. I don’t think any diffractive waveguide would be widely considered good enough for movies and good photographs, but they are good enough to show lines, arrows, and text. But let me add a key caveat, what all companies demonstrate are invariably certainly cherry-picked samples.
Field of View (FOV)
While the Argos 30-degree FOV is considered too small for immersive games, for many “enterprise applications,” it should be more than sufficient. I discussed why very large FOVs are often unnecessary in AR in this blog’s 2109 article FOV Obsession. Many have conflated VR emersion with AR applications that need to support key information with high transparency, lightweight, and hands-free. As Professor and decades-long AR advocate Thad Starner pointed out, requiring the eye to move too much causes discomfort. I make this point because a very large FOV comes at the expense of weight, power, and cost.
Key Feature Set
The diagram below is from DigiLen on the ARGO and outlines the key features. I won’t review all the features, but I want to discuss some of their design choices. Also, I can’t comment on the quality of their various features (SLAM, WiFi, GPS, etc.) as A) I haven’t extensively tried them, and B) I don’t have the equipment or expertise. But at least on the surface, in terms of feature set, Argo compares favorably to the Hololens 1 and 2, if having a smaller FOV than the Hololens 2 but with much better image quality.
Most realistic enterprise-use models for AR headsets include significant, if not exclusively, hands-free operation. The basic idea of mounting a display on the user’s head it so they can keep their hands free. You can’t be working with your hands and have a controller in your hand.
While hand tracking cameras remove the need for the physical controller, they do not free up the hands as the hands are busy making gestures rather than performing the task with their hands. In the implementations I have tried thus far, gestures are even worse than physical controllers in terms of distraction, as they force the user to focus on the gestures to make it (barely sometimes) work. One of the most awful experiences I have had in AR was trying to type in a long WiFi password (with it hidden as I typed by asterisk marks) using gestures on a Hololens 1 (my hands hurt just thinking about it – it was a beyond terrible user experience).
Similarly, as I discussed with SadlyItsBradley about Meta’s BCI wristband, using nerve and/or muscle-detecting wristbands still does not free up the hands. The user still has their hands and mental focus slaved to making the wristband work.
Voice control seems to have big advantages for hands-free operation if it can work accurately in a noisy environment. There is a delicate balance between not recognizing words and phrases, false recognition or activation, and becoming too burdensome with the need for verification.
Skull-Gripping “Glasses” vs. Headband or Open Helmet
In what I see as a futile attempt to sort of look like glasses (big ugly ones at that), many companies have resorted to skull-gripping features. Looking at the skull profile (right), there really isn’t much that will stop the forward rotation of front-heavy AR glasses unless they wrap around the lower part of the occipital bone at the back of the head.
Both the ARGO (below left) and Panasonic’s (Shiftall division) VR headsets (right two images below) take the concept of skull-grabbing glasses to almost comic proportions. Panasonic includes a loop for the headband, and some models also include a forehead pad. The Panasonic Shiftall uses pads pressed against the front of the head to support the front, while the ARGO uses an oversized large noise bridge as found on many other AR “glasses.”
ARGO supports a headband option, but they require the ends of the temples with the skull-grabbers temples to be removed and replaced by a headband.
As anyone who knows anything about human factors with glasses knows, the ears and the nose cannot support much weight, and the ears and nose will get sore if much weight is supported for a long time.
Large soft nose pads are not an answer. There is still too much weight on the nose, and the variety of nose shapes makes them not work well for everyone. In the case of the Argo, the large nose pads also interfere with wearing glasses; the nose pads are located almost precisely where the nose pads for glasses would go.
Bussel/Bun on the Back Weight Distribution – Liberating the Design
As was pointed about by Microsoft with their Hololens 2 (HL2), weight distribution is also very important. I don’t know if they were the first with what I call “the bustle on the back” approach, but it was a massive improvement, as I discussed in Hololens 2 First Impressions: Good Ergonomics, But The LBS Resolution Math Fails! Several others have used a similar approach, most notably with the Meta Quest Pro VR (it has very poor passthrough AR, as I discussed in Meta Quest Pro (Part 1) – Unbelievably Bad AR Passthrough). Another feature of the HL2 ergonomics is the forehead pad eliminates weight from the nose and frees up that area in support of ordinary prescription glasses.
The problem with the sort-of-glasses form factor so common in most AR headsets today is that it locks the design into other poor decisions, not the least of which is putting too much weight too far forward. Once it is realized that these are not really glasses, it frees up other design features for improvement. Weight can be taken out of the front and moved to the back for better weight distribution.
ARGO’s Eye-Relief Missed Opportunity for Supporting Normal Glasses
Perhaps the best ergonomic/user feature of the Hololens 1 & 2 over most other AR headsets is that they have enough eye relief (distance from the waveguide to the eye) and space to support most normal eyeglasses. The ARGO’s waveguide and optical design have enough eye relief to support wearing most normal glasses, but still, they require specialized inserts.
You might notice some “eye glow” in the CNET picture (above right). I think this is not from the waveguide itself but is a reflection off of the prescription inserts (likely, they don’t have good anti-reflective coatings).
A big part of the problem with supporting eyeglasses goes back to trying to maintain the fiction of a “glasses form factor.” The nose bridge support will get in the way of the glasses, but the nose bridge support is required to support the headset. Additionally, hardware in the “brow” over the eyes could have been moved elsewhere, which may interfere.
Another technical issue is the location and shape of their optical engine. As discussed earlier, the Digilens engine shape causes issues with jutting into the front of glasses, resulting in a large brow over the eyes. This brow, in turn, may interfere with various eyeglasses.
It looks like Argo started with the premise of looking like glasses putting form ahead of function. As it turns out, they have what for me is an unhappy compromise that neither looks like glasses nor has the Hololens 2 advantage of working with most normal glasses. Starting from the comfort and functionality as primary would have also led to a different form factor for the optical engine.
Conclusions
While MicroLED may hold many long-term advantages, they are not ready to go head-to-head with LCOS engines regarding image quality and color. The LCOS engines are being shown by multiple companies that are more than competitive in size and shape with the small MicroLED engines. The LCOS engines are also supporting much higher resolutions and larger FOVs.
Lumus, with their Z-Lens 2-D reflective waveguides, seems to have a big advantage in image quality and efficiency over the many diffractive waveguides. Allowing the Z-lens to be encased without an air gap adds another significant advantage.
Yet today, most waveguide-based AR glasses use diffractive waveguides. The reasons include there being many sources of diffractive waveguides, and companies can make their own custom designs. In contrast, Lumus controls its reflective waveguide I.P. Additionally, Lumus has only recently developed 2-D reflective waveguides, dramatically reducing the size of the projection engine driving their waveguides. But the biggest reason for using diffraction waveguides is that the cost of Lumus waveguides is thought to be more expensive; Lumus and their new manufacturing partner Schott Glass claimed that they will be able to make waveguides at competitive or better costs.
A combination of cost, color, and image quality will likely limit MicroLEDs for use in ultra-small and light glasses with low amounts of visual content, known as “data snacking.” (think arrows and simple text and not web browsing and movies). This market could be attractive in enterprise applications. I’m doubtful that consumers will be very accepting of monochrome displays. I’m reminded of a quote from an IBM executive in the 1980s when asked whether resolution or color was more important said: “Color is the least necessary and most desired feature in a display.”
Not to pick on Argo, but it demonstrates many of the issues with making a full-featured device in a glasses form factor, as SLAM (with multiple spatially separated cameras), processing, communication, batteries, etc., the overall design strays away from looking like glasses. As I wrote in my 2019 article, Starts with Ray-Ban®, Ends Up Like Hololens.
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