Introduction

Several technology demonstrations stood out to me at Display Week (DW) 2025. This article will cover Playnitride’s Quantum Dot (QD) based full-color MicroLED, combined with Lumus’s geometric (also known as reflective waveguide) technology.

As I hinted in my last article, “Rivet Industries Using Lumus Waveguides for Military & Industrial AR, Lumus showed me in private a “fantastically tiny MicroLED projector.” This development came on the heels of rumors that a 30-degree Lumus Z-Lens is included in Meta’s Hypernova glasses, as discussed in Meta Hypernova and Google AR/AI Glasses – Lumus & Avegant Inside, both of Which Utilize LCOS MicroDisplays. I also wrote about a PlayNitride and Lumus waveguide demo at AR/VR/MR 2023 (see: PlayNitride (Blue with QD Conversion Spatial Color)) and about PlayNitride at Display Week 2024 using a diffractive waveguide with a lower resolution display (see: PlayNitride).

I know it has been a lot on Lumus lately, but that’s just how the news and information came to me and what I found exciting. I had no idea that Lumus would be in Rivet, and as far as I know, I was the first to identify that Lumus was inside, so I wanted to publish it promptly. Then, this article made sense to follow up on that one.

In the next article, I plan to follow up with more about Avegant’s LCOS engine, featuring an Applied Materials diffractive waveguide, and provide another clue that Avegant’s and Applied Materials’ projectors and waveguides are likely being used in the Google/Android XR prototypes. I got to try on the Avegant 30-degree biocular prototype, and overall, it looked good.

AWE on June 10-12, 2025 (I’m Attending and Speaking)

For anyone interested in meeting me, I will be attending AWE on June 10-12. I’m happy to meet with both companies and individuals. Please email me at meet@kgontech.com if you want to meet. I will also be speaking on Thursday, June 12th, from 10:30 AM to 10:55 AM in the Promenade Room 104 B.

Lumus and PlayNitride at Display Week 2025

Lumus had a running demo in the PlayNitride booth at DW 2025. The demo featured a PlayNitride 720×720 (0.18″ diagonal, ~3.2mm on a side) 4.5 µm pixel (pitch) full-color QD MicroLED display, accompanied by a small but unoptimized projector engine, and a 50-degree (diagonal) Lumus Maximus waveguide.

I’ve been impressed with Lumus Maximus’s waveguide compared to diffractive waveguides since I first saw it (see: Exclusive: Lumus Maximus 2K x 2K Per Eye, >3000 Nits, 50° FOV with Through-the-Optics Pictures). The engine in that article utilized a Compound Photonics 2048×2048 LCOS device with a 3-micron pixel pitch. Lumus switched to RAONTECH’s 1440×1440 with a 4.3-micron pixel after Snap acquired Compound Photonics (see: Exclusive: Snap Buying Compound Photonics (LCOS and MicroLED)). RAONTECH recently announced that its new 1440×1440 device features a 3-micron pixel and a 0.24″ diagonal display.

Lumus’s DW demo is a “quick and dirty” proof-it-works setup, with the optics held in place by a small optical bench and a large “pull” lens in front of the waveguide, primarily to prevent people from touching the setup. The lens also had the effect of keeping cameras at a distance and magnifying the image (see the upper right picture below). Unfortunately, there was great content being shown, but at least you can see that the white lines are white across the image (unlike many diffractive waveguides).

Since the display form factor is square, the horizontal and vertical field of view (FOV) are ~35 degrees, resulting in about 20 pixels per degree PPD, which is larger than some would desire, but within the bounds of general acceptability considering it is an optical see-through (OST) device. The placard on the demo states that it outputs more than 700 “white” nits (to the eye), which is largely a function of Lumus Maximus waveguides that are over 90% transparent.

Fantasically Tiny Projector

Lumus states that the current design outputs approximately 0.7% of the nits of the display, which, although it may seem small, should be about five to seven times more efficient than a diffractive waveguide. PlayNitride, in its presentation, claims that the MicroLED is capable of exceeding 500K nits, which at 0.7% would be 4,500 nits via the waveguide to the eye. I’m unsure if there are lifetime or other practical issues with driving PlayNitrides MicroLEDs hard enough to produce more than 500K (white) nits. As I explained in Caution on Comparing Nits/WattLED with Different Waveguides, there are many ways companies specify nits. I also want to note that white/full-color nits and power consumption can’t be compared fairly to, say, “green only nits,” as much of the perceived “nits” are in green, and generally, red is much less efficient than blue or green.

While the Maximus connected to the PlayNitride 720×720 is small, it may not be dramatically smaller than the 3-chip (R, G, and B) 640×480 X-Cube projectors I have seen using Jade Bird Display’s MicroLEDs. Lumus then showed me privately a more optimized projector that they have working with the same PlayNitride MicroLED, which they did not want to show on the floor, which I have since dubbed “the fantastically tiny projector.”

Shown below, from left to right, are the Lumus Maximus 50+ degree waveguide with a 1440×1440 LCOS, an older 1920×1080 with a 5.6µ pixel PlayNitride engine, the 720×720 engine shown at Display Week, and the tiny, optimized 720×720 engine. The engine is only a few millimeters bigger than the display in every dimension. Note that the tiny projector’s waveguide has not been cut to shape for glasses. Based on the pictures, I would estimate the volume of Lumus’s optimized prototype engine to be approximately 0.15 cubic centimeters (or less, depending on the definition of “counts”).

While the PlayNitride display is not yet ready for production, the tiny combination shows where this technology is headed in a few years. We can expect the pixel size to continue shrinking, enabling an increase in angular resolution while maintaining the field of view (FOV). Lumus states that the current Maximus design supports a field of view (FOV) up to 60 degrees, and their Z-Len technology is capable of exceeding 70 degrees (in glass, not exotic, but very high-index Silicon Carbide).

PlayNitride Diffractive Waveguide Demo

PlayNitride also had a diffractive waveguide demo in their booth, which they discussed in their presentation. It also has a tiny projector, considering that it is full color. The diffractive waveguide had a 30-degree field of view (FOV). It claims to support over 500 nits, but once again, we don’t know under what conditions or for how long.

The Lumus Maximus waveguide demo was significantly brighter than the diffractive waveguide’s demo using the same device, despite having about 2.8 times the field of view (FOV) area. However, I have no information on how hard each display device was driven. However, it does make Lumus’s claim of being more than five times more efficient than diffractive waveguides plausible. I should note that different diffractive waveguides have different efficiencies.

Below is an image I captured through the Diffractive waveguide demo in the PlayNitride booth. Even with the lack of content, it is evident that the parts intended to be white exhibit significant color variation across the waveguide’s field of view (FOV). The picture also shows some light capture rainbows (blue streaks on the left and lower right).

Not Enough Content to Judge Display Quality

Unfortunately, PlayNitride had very little content to judge the image quality of their displays. Usually, this means that the devices are not up to being judged on display quality. The very simple images PlayNitride provided can easily conceal everything from bad or dead pixels to issues with color accuracy and uniformity.

My general experience and skepticism, based on demo content seen at shows, suggest that the PlayNitride MicroLEDs are far from ready for production, or they would have shown better demo images.

More on PlayNitride

I first took notice of PlayNitride back in 2018 when it was rumored that they were working with Apple on MicroLEDs for watches (see the 2018 MICROLED-info article). A couple of years later, it was rumored that Apple decided to back off or delay its planned use of MicroLEDs in watches, as they were not yet mature. PlayNitride has continued to improve its MicroLED development.

PlayNitride manufactures blue MicroLEDs and then utilizes quantum dots to convert the blue light to red or green. Playnitride offers three ranges of products, categorized by pixel size and display backplane. For products like watches, smartphones, and moderately small displays, it will singulate individual pixels and transfer them to a TFT on a glass or plastic backplane, which may or may not be transparent. For very large displays, the full-color pixels are plugged into a printed circuit board (PCB). However, for the very small microdisplays used in AR/smart glasses, the pixel sizes are so small that transferring individual pixels is impractical; therefore, the entire display array of MicroLEDs is flipped and bonded to a CMOS substrate.

Most other companies flip whole wafers of MicroLEDs onto CMOS wafers. MicroLED wafers are smaller than state-of-the-art CMOS wafers. Some companies flip multiple smaller whole LED wafers onto a 12″ CMOS wafer, which wastes a significant part of the CMOS wafer. Some companies compromise and make 8″ LED wafers to make 8″ CMOS wafers. For MicroDisplays, PlayNitride tests and singulates whole displays/devices on a 12″ CMOS wafer and the MicroLED wafer before combining them (right). Without delving into all the details, each method has its advantages and disadvantages.

PlayNitride shows the chart below in the DW 2025 Presentation. Note that this is only applicable to “full color” MicroLED microdisplays. I covered Raysolve and Saphlux in my SID Display Week 2024 – MicroLEDs for AR, and will be updating my findings in an upcoming article about MicroLEDs at DW 2025. Raysolve showcased a working ~8-micron pixel pitch 320×240 full-color MicroLED in their booth at DW 2025. I must point out that none of these devices are currently in production, so it is impossible to know who is ahead of whom.

Using QD conversion appears to be the most straightforward method for producing full-color MicroLEDs, but it has its drawbacks. The most obvious is that the reds and greens are not as pure or saturated and typically contain some unconverted blue. There is also typically some “crosstalk” from the adjacent color’s blue light stimulating the wrong quantum dot (QD). Some propose using a UV simulation that is covered with red, green, and blue QD with a UV filter to block all the unconverted light. Both JBD and Innovision, among others, have developed stacked native red, green, and blue LED layers on top of the CMOS backplane. Once again, none of these are in production, and each of these full-color MicroLED microdisplay methods has its technical and manufacturing advantages and disadvantages.

Many of the pros and cons of various approaches to making full-color MicroLED microdisplays were discussed in “SID Display Week 2024 – MicroLEDs for AR.”

I also want to note that TCL just “launched” their RayNeo X3 Pro glasses with dual 640×480 X-Cube three displays that are X-Cube combined. These glasses were supposed to have applied Materials waveguides. Applied Materials waveguides are also likely in the Google/Android XR smartglasses (but which uses LCOS displays) shown at Google I/O and their TED talk (see Meta’s Hypernova glasses, as discussed in Meta Hypernova and Google AR/AI Glasses – Lumus & Avegant Inside, both of Which Utilize LCOS MicroDisplays)

Conclusion

While I don’t think any of the single-chip, full-color MicroLED solutions are ready for production anytime soon, the Lumus engine with the PlayNitride device demonstrates the potential for how tiny/insignificant the projector engine can become.

According to Lumus, the Maximus should be more than 5 times the light efficiency of diffractive waveguides for the same size field of view (FOV) and eye box. If true, this is a massive advantage for Lumus/Reflective waveguides because not only can the displays be brighter, but more importantly, they require significantly less power for the same brightness. Typically, power goes up non-linearly with brightness as the LEDs self-heat. As I repeatedly say about AR glasses and power consumption, “Amateurs worry about battery life, the pros worry about heat management.” Based on my experience, I also expect the Lumus waveguides to have much better color and brightness uniformity.