Introduction

SID Display Week 2025 is coming to San Jose, CA, May 11–16. Last year’s event was a whirlwind of groundbreaking innovations. While I managed to share insights on Jade Bird Display’s MicroLED Compensation, I’ve been sitting on information and photos on many other companies from Display Week 2024. With this year’s show right around the corner, it’s time to dust off those notes and many photos and write about the display and optics technology I found at last year’s Display Week, which was so interesting that I want to go back again this year.  

For this article, I’m going to cover the LCOS-related companies I met with at Display Week. I plan on writing three or four articles to cover everything I saw on MicroLEDs, OLEDs, and Optics from Display Week 2024. I learned about a lot of AR/MR-related developments at Display Week 2024 and why I am going to it again this year. As I discussed in SPIE AR/VR/MR 2025 Next Week (with comments on CES, Display Week, & AWE), each conference tends to cover different aspects of displays and optics for AR/VR/MR. I will be mixing in some information from these other conferences that pertain to technology, as shown at Display Week 2024.

Partnering with SID and Discount Code

I’ve partnered with SID to share my insights from Display Week — past, present, and future. If you’re planning to attend Display Week, SID has provided the code DW25KARL for a free exhibit hall pass — don’t miss the chance to explore the latest innovations shaping the future of displays.

LCOS is still the display of choice for full-color waveguide AR glasses designs

While (mostly green only) MicroLEDs seem to garner most of the attention these days, they are still expensive and relatively low resolution, and the roadmap to full-color still has some uncertainties. OLEDs, for physics reasons, don’t work with waveguides.

LCOS is still the display technology of choice for full-color,  higher-resolution, and larger FoV (>30 °) waveguide AR glasses. The key reasons include:

1. Cost (relative to MIcroLED and DLP) and availability
2. Resolution and variety of resolutions and form factors
3. Optical design experience leading to size reductions
4. Full color for a little more than monochrome
   1. Color is still a big problem for MicroLEDs
5. Brightness/efficiency with waveguides (due to relatively low étendue)
   1. Much lower étendue than MicroLEDs
   1. Field sequential color (FSC) results in a smaller pixel and thus a smaller device for better étendue. FSC can have color breakup due to eye movement.

LCOS’s étendue advantages (over MicroLED)

Something often overlooked when comparing LCOS to MicroLEDs is the issue of étendue. Most of the LED (large or small) output Lambertian (somewhat diffuse) light (for more on étendue, Lambertian, and related topics, see Collimation, Étendue, Nits (Background for Understanding Brightness). Waveguides can only accept highly collimated light, and their entrance pupils are relatively small. With MicroLEDs, the difference between the emitter size and pixel pitch allows for some collimation with microlens arrays (MLAs). However, with LCOS, the area of the illuminating LEDs sets the étendue limit. The area of the LCOS’s illuminating LEDs is much smaller than the area of the MicroLED displays. This results in LCOS with LED illumination coupling much more efficiently into waveguides.

MicroLED’s big efficiency advantage over LCOS is that MicroLED’s power consumption is roughly proportional to the Average Pixel Value (APV, also known as Average Pixel Lit = APL) of the whole image. With most LCOS designs, the whole display is illuminated regardless of the AVP. In many, if not most, AR applications, the AVP is likely to be less than 10%; otherwise, the display would block out the real world. However, there is a design dilemma of what to do if it is possible to display a high AVP image. A MicroLED with an AVP of 100% can consume and thus have to dissipate several times the power of an LCOS design for the same brightness. One approach, as used on many larger OLED displays, would be to limit the overall brightness based on content.

The chart below was created by Bernard Kress (of SPIE and Google and formerly a technical leader on Microsoft Hololens 1 &2). The charts show different types of display content and their typical APV/APL for different types of glasses/content. On the other axis, power usage is displayed. The chart gives a rough idea of the concept of power consumption versus content (APV/APL) at a high level.

A key point on the chart is where MicroLED (red line) and ordinary LCOS (cyan/light-blue line) cross at about 12% APL. For small APL, the advantage of MicroLEDs to turn off most of the pixels “wins,” but above ~12%, LCOS, with its étendue advantage, wins. Kress shows “local dimming,” which uses arrays of mini-LEDs to illuminate LCOS (green line), significantly moving the crossover point. How much local dimming helps is a function of a lot of factors, including the size of the mini-LEDs, the number of LEDs that are arrayed, and the location of the content. As Kress’s chart shows, with miniLED local dimming LCOS, the crossover moves to about ~3%.

Meta’ Zonal Illumination (= Local Dimming) Non-Emissive Displays for AR Glass of LCOS

Between Display Week 2024 and AR/VR/MR 2025, Meta has presented papers on LCOS, MicroLEDs, and Laser Beam Scanning (LBS) for use in AR. In other words, they cover everything, or as I have said on many occasions, “In Mixed Reality, if you can dream of it, Meta has tried it.” After all, Meta is spending about $1B per month on MR.

Fenglin Peng of Meta’s Reality Labs presented Zonal Illumination Non-Emissive Displays for AR Glass. They discussed what Meta calls “Zonal Illumination,” which is local dimming. They show 12 x 12 (144) dimming zones. What was shown was an R&D proof of concept. I suspect the 12 x 12 array of mini-LEDs is too large to be what is known as being “étendue-matched” to the entrance pupil of the waveguide. If the array is too large, then due to étendue, part of the light will not couple in and will be lost.

Avegant Spotlight (Local Dimming)

Avegant showed a more modest but aimed at a real product (compared to Meta’s research study) 3 x 3 segmented illumination at SPIE AR/VR/MR in January 2024. The diagram below combines several of Avegant’s concepts, including segmented diming and a “reflective waveguide” to eliminate the large PBS and LED illumination for a small form factor. Avegant said that the LED array is small enough to be étendue-match. However, the small number of segments will mean that it will only work well if the content is not spread over the whole display area.

Ultra High Brightness Color Sequential Front-lit LCOS by Himax (at Display Week 2024)

Ultra High Brightness Color Sequential Front-lit LCOS by Himax Yuet-Wing LI from Himax presented Himax’s front-lit LCOS to reduce the size of the LCOS projector engine. Their design uses a “polarized waveguide,” which is likely different from the “reflective waveguide” used by Avegant in their Spotlight design (discussed above). You should also note that the Himax illumination waveguide is against the panel, whereas in the Avegant design, the light passes through the projection optics to illuminate the panel.

FocaLight small LCOS engine (at CES and AR/VR/MR 2025)

On the subject of small LCOS engines, at both CES and AR/VR/MR 2025, a new company, Focal Light, showed an LCOS projector engine that they say is only 0.7cc (right). I don’t know how they achieved this size, but it is about half the size of the engines shown in the Himax presentation and Avegant’s engines.

Citizen Fine Device Myota Development Center – FLCOS and other LCOS Foundary (Display Week 2024)

Citizen, most famous for watches, has many different divisions/groups. Citizen Fine Devices (CFD) started developing FLCOS (ferroelectric-LCOS, also known as fast-LCOS) device manufacturing for Displaytech. This was sold to Micron, which, in turn, sold it to Citizen. So now Citizen sells the FLCOS devices that it manufactures. Citizen also provides foundry services to make Twisted Nematic (Tn) and Vertically Aligned Nematic (Van) liquid crystal LCOS designs for other companies.

CFD showed many different devices and applications for its FLCOS technology, which is used for both display and electronic shutters (lower left). CFD also makes Quarter Waveplates and high-speed shutters that could be useful components for use in Mixed Reality.

FLCOS has the advantage of being about 10X faster than Tn with similar cell geometries. The big downside of FLCOS is that when it is “DC-Balanced,” it produces a “negative image,” and thus, the illumination must be turned off about ½ the time. Tn and Van LCOS, when DC-balanced, produce a positive image, so the light does not have to be turned off while balancing. The DC balancing problem was a big problem for very bright projectors, but it is less of an issue for LED-illuminated small projectors in AR, where the LEDs can be driven harder for a shorter time period.

CFD claims FLCOS has an advantage over Tn and Van in terms of “cross-talk” (right), which I think is their term for  “lateral fields.” Lateral fields occur when light and dark pixels are next to each other, which causes electric field lines to go between the adjacent pixels rather than between the pixel mirror and the ITO coating of the top glass. These lateral fields can cause adjacent pixels to bleed together, particularly when the values are very different.

Creal Using FLCOS (AR/VR/MR 2025)

Creal, which is developing a Light Field headset, is leveraging the switching speed of FLCOS (likely from CFD) to produce time-sequential light fields for its headset device. While Creal has not reduced the headset to its final form factor, it has been showing continuous progress in developing its technology. The photographs below are from their private room at AR/VR/MR 2025.

RaonTech LCOS (plus some OLED and MicroLED development) at Display Week 2024

Raontech’s main business is LCOS, and I see many companies using their panels. At SID Display Week 2024, they showed AR glasses made by Singularity, Geding, and Lumus using their LCOS devices.

The picture below shows their many LCOS panels, plus some work they have jointly developed with Micro-OLED and MicroLED companies, where RaonTech designed the CMOS backplane for controlling the pixels.

VitreaLab Laser Quantum Light Chip for Illuminating LCOS (Display Week 2024)

VitreaLab has developed a “quantum light chip” that routes laser light for illuminating either LCOS or small LCDs used in VR. Lasers output light with near zero etendue, which results in the light coupling very efficiently into waveguides or other optics with extremely low losses.

Their booth at Display Week 2024 included a demonstration of their technology using an LCOS device with a Digilens waveguide (below).

Meta’s laser routing “photonic integrated circuit,” with Zonal Illumination and using FLCOS (AR/VR/MR 2024)

In another example that proves my statement, “if you can dream of it, Meta has tried it,” Meta Labs, in a presentation at AR/VR/MR 2025, showed a similar photonic integrated circuit (PIC) for routing lasers to illuminate LCOS. At least superficially, it looks a lot like VitreaLabs PLC.

In Meta Lab’s design, the PIC illuminates the LCOS device with routed polarized laser light, which passes back through the PIC after the LCOS has modulated the light. Meta’s presentation goes on to discuss the concept of selective dimming with the PIC and the fact that FLCOS would be a good LCOS technology to use with their PIC illumination.

Conclusion

MicroLEDs get most of the attention these days in optical see-through (OST) mixed reality. However, LCOS involves a lot of “physics,” particularly when it comes to using waveguides. Companies are still innovating to make smaller and more efficient LCOS designs.

Additionally, Meta is spending over $1B/month with multiple teams of researchers. They cover all bases for displays and optics for mixed reality. At AR/VR/MR 2025, they presented papers showing MicroLEDs, Laser Beam Scanning (LBS), and LCOS/FLCOS, thus my “If you can dream it, Meta has tried it” saying.